Editing List of inconsistencies in the Halo series

{{Status|RealWorld}}
{{Title|List of inconsistencies in the ''Halo'' series}}<choose>
<option>{{Quote|no=four|Science Team Leader|ONI Commander|Science Team Leader|ONI Commander|q1=Combined science team analysis gives us considerable conviction that the related events are credible.|q2=But they contradict everything we know about the Didact! [...] The terminal dialogs--|q3=The terminal dialogs may themselves be questionable, in light of this new testimony.|q4=I lodge my strong suspicion.|An in-universe acknowledgment of the conflicts between the [[Terminal (Halo 3)|''Halo 3'' terminals]] and ''[[The Forerunner Saga]]''.}}</option>
<option>{{Quote|So, um, how come do you figure stuff looks different sometimes? Like guns, or [[Thel 'Vadam|the Arbiter]]? Like do you remember being more purpler? I do! Eh, maybe it's just my eyes getting smart, but I swear sometimes it's like [[UNSC Forward Unto Dawn|a whole spaceship is different]] and nobody says anything. I mean was the [[Gravemind]] always [[Halo 2: Anniversary|so much scary]]? I dunno, [[Halo 2|he was like a big puppet, big flabby thing]]. Eh, maybe it's just me that notices stuff.|[[Dimkee Hotay]], noting cosmetic retcons in the [[Halo universe]].}}</option></choose>
This list is compiled to show the various discrepancies spotted in the [[Halo universe|''Halo'' universe]]. Inconsistencies on the list are divided into two types: '''internal''' and '''external'''. Internal inconsistencies refer to discrepancies which occur within a single source, while external inconsistencies are conflicts between two or more sources.

It is often difficult to decide which resource is "superior" to another, so conflicts are mostly listed in a chronological order. Likewise, it can rarely be conclusively determined whether a conflict is the result of an oversight on part of the author or editor(s) or an intentional [[Wikipedia:Retroactive continuity|retcon]], unless this is specifically confirmed by the developers of the ''Halo'' franchise; such cases are noted accordingly. For more information, see [[Halopedia:Canon policy|here]]. There have been a number of cases in which an apparent inconsistency arises within an individual piece of media, only to receive a canonical workaround in another source; an example of this is the shared designation "Type-47 Scarab" for the two different Scarab models appearing in ''Halo 2'' and ''Halo 3'', something that was eventually clarified as "a UNSC administration quirk".<ref>[https://www.halowaypoint.com/en-us/universe/vehicles/scarab '''Halo Waypoint''': ''Scarab'']</ref> For inconsistencies that have since been resolved by other ''Halo'' media, see [[List of rectified inconsistencies in the Halo series]].

Many inconsistencies on this page are provided possible explanations, although it should be noted that these are only unofficial theories unless otherwise stated, and may not reflect the franchise developers' stance on the matters in question. If you think you can explain an inconsistency, do so [[Talk:List of inconsistencies in the Halo series|here]], on this article's talk page.

==Inconsistencies==
In instances in which two or more works have been developed concurrently and released within a short span of time of one another (''e.g.'' games and their marketing material), the "primary" work takes precedence on this list even if released marginally later than the "secondary" one. For example, conflicting information in ''Halo: The Fall of Reach'' is said to contradict ''Halo: Combat Evolved'', even though the novel was released slightly earlier than the game. Conflicts which are persistent throughout multiple sources are listed in the "Several sources" section.

===''Halo: The Fall of Reach''===
{{Main|Halo: The Fall of Reach}}

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*The [[Eridanus II]] space dock is erroneously stated to be located in the [[Epsilon Eridani system]] in the chapter heading for Chapter 10.<ref name="for81">'''Halo: The Fall of Reach (2001)''', ''page 81''</ref> Throughout the rest of the book, Eridanus II is correctly referenced as being located in the similarly named [[Eridanus system]].<ref name="fornumbers">'''Halo: The Fall of Reach (2001)''', ''pages 13, 21, 75''</ref>

*When Dr. Halsey and the Spartans are on a Pelican leaving the Damascus Testing Facility, Halsey tries to adjust her glasses but can't due to her space helmet. Despite this she is later said to tap her lip in thought.

*The time stamp for Chapter 23 is labeled "0500 hours, July 18, 2552",<ref>'''Halo: The Fall of Reach''', ''page 211'' (2001); ''page 242'' (2010)</ref> even though the events portrayed take place after the preceding chapters which occurred over the evening of July 18; the previous chapter begins at 2010 hours that day.<ref>'''Halo: The Fall of Reach''', ''page 200'' (2001); ''page 230'' (2010)</ref>
**It is possible that while Chapters 18-22 are labeled as occurring on July 18, they are supposed to take place on July 17. The time stamps suggest a day-long pause between Chapters 17 and 18,<ref>'''Halo: The Fall of Reach''', ''page 181'' (2010)</ref> and although this can be justified by [[Michael Stanforth|Admiral Stanforth]]'s [[Battle Group Leviathan]] taking more than several hours to reach the Sigma Octanus system, the description of the battle on the surface suggests the events occurred during the same day as the initial space battle. Alternatively, the date in Chapter 23's heading could simply be a mistake, with the intended date being July 19. This is corroborated by the second [[Data Drop]], in which Stanforth sends a message to [[Margaret Parangosky|Admiral Parangosky]] in the immediate aftermath of the [[Battle of Sigma Octanus IV]] at 2300 hours on July 18, 2552.

*When John-117 reflects on his life in August 2552, he notes that the Spartan-IIs were conscripted "twenty-five years ago".<ref name="tfor2502010">'''Halo: The Fall of Reach''', ''page 250'' (2010)</ref> The candidates were actually kidnapped in 2517, nearly 35 years prior.

*John-117 internally notes that he had "overheard" Dr. Halsey mention Chief Mendez departed to train a new group of Spartans.{{Ref/Reuse|tfor2502010}} Earlier in the novel, Halsey explicitly tells John and the other Spartan-IIs of Mendez's future role.<ref>'''Halo: The Fall of Reach''', ''page 121'' (2010)</ref>

*On August 30, Cortana mentions that her test with John-117 and the Mark V MJOLNIR occurred "this morning",<ref>'''Halo: The Fall of Reach''', ''page 304'' (2010)</ref> even though the test took place a day earlier.<ref>'''Halo: The Fall of Reach''', ''page 280'' (2010)</ref>

*[[Chief Petty Officer]] [[McRobb]] states that his posting on ''[[Fermion]]'' was part of the UNSC's new policy to staff [[Remote Scanning Outpost]]s with their most competent personnel—a policy that was put into effect following the [[Battle of Sigma Octanus IV]] just over six weeks earlier. Despite this, he notes that he had spent three months preparing his crew for the new assignment.<ref>'''Halo: The Fall of Reach''', ''pages 319-320'' (2010)</ref>

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*[[Grunt]]s are said to be about a meter tall.<ref>'''Halo: The Fall of Reach''', ''page 1''</ref> Subsequent material portrays them as roughly 1.5 meters tall.

*John-117 notes that he ''"had seen a disarmed Jackal fight hand to hand rather than pick up a nearby human assault rifle"'' as an example of the Covenant's abhorrence of human weaponry.<ref>'''Halo: The Fall of Reach''', ''page 201'' (2001); ''page 231'' (2010)</ref> While this may apply to most of the Covenant species, such behavior is rather out of character for the Kig-Yar in light of their gameplay tendency to flee from melee combat. In addition, later backstory has established the Kig-Yar as opportunistic mercenaries rather than faithful adherents of the Covenant religion, making the described behavior seem even more out of place. Additionally, in ''[[Halo: Reach]]'' Covenant Elites and Grunts will occasionally use human weapons, such as [[M247H machine gun|M247]] and [[M41 Vulcan|M41]] turrets encountered on the battlefield (though like all NPCs they cannot pick up dropped weapons). Furthermore, in [[Halo 2 Limited Collector's Edition Manual|a letter]] to [[Prophet of Truth]] written by [[Thel 'Vadam]]ee, the Sangheili encourages use of human weapons if necessity requires it.<ref>'''[[Halo 2 Limited Collector's Edition Manual]]'''</ref>

*Covenant [[plasma pistol]]s are said to have barrels in one description,<ref>'''Halo: The Fall of Reach''', ''page 203'' (2001); ''page 233'' (2010)</ref> even though the weapons do not possess barrels of any sort as the plasma projectiles are generated between the pistol's two "claws".

*It is stated that the [[Hunter]]s' [[assault cannon]]s ''"seemed almost as powerful as the stationary plasma cannons the Jackals used."''.<ref>'''Halo: The Fall of Reach''', ''page 207'' (2001); ''page 237'' (2010)</ref> In the games, the Hunters' weapons are considerably more powerful than the Covenant's [[Shade|stationary turrets]], which are operated predominantly by Grunts and Elites.

*When the Master Chief kills Elites and Jackals aboard Gamma Station, the aliens are said to bleed blue and green [[blood]], respectively. Both species' blood is actually purple or purple-blue in the Sangheili's case.<ref>'''Halo: The Fall of Reach''', ''page 327'' (2001); ''page 367'' (2010)</ref>

*The novel repeatedly describes [[slipspace]] ruptures as being green.<ref>'''Halo: The Fall of Reach''', ''pages 145, 286'' (2001); ''pages 170, 322'' (2010)</ref> Although no slipspace phenomena had been shown in visual media at the time of the novel's writing, all subsequent media has depicted slipspace ruptures as blue; the effects associated with slipspace-based [[teleportation]] are most often depicted as yellow or orange.

*In ''Halo: The Fall of Reach'', [[Aki Hikowa]] and [[Ellen Dowski]] are female officers of the ''Pillar of Autumn''. However, on the level ''[[The Pillar of Autumn (Halo: Combat Evolved level)|The Pillar of Autumn]]'', the bridge has no female members.
**This may imply that, like modern navy ships, the ''Autumn'' has rotating shifts. The obvious Doylist explanation is that no female crew members were modeled.

*[[William Lovell]]'s eyes are stated to be green in ''Halo: The Fall of Reach'',<ref>'''[[Halo: The Fall of Reach]]''', page 133</ref> but in ''Halo: Combat Evolved'', the ''Autumn'''s crew has no green-eyed members.
**This is likely a result of game engine limitations, or due to rotating shifts, Lovell was simply not present on the bridge at the time.

*In ''Halo: The Fall of Reach'', the description of the ''Pillar of Autumn'' is considerably different from its ''Halo: Combat Evolved'' incarnation. The bridge is described as having a command chair and a curved viewport; in ''Halo: Combat Evolved'', this chair is absent and the window consists of several flat sections. The novel also describes the bridge as being extremely cramped, with only a meter of space between the command chair and the other stations,<ref name="for277">'''Halo: The Fall of Reach''', ''page 277''</ref> while in the game, the bridge is clearly more spacious. According to the novel, there is also an elevator leading directly from the engine room to the bridge.{{Ref/Reuse|for277}} In the game, the engineering and the bridge are on the same level, and there are no doors which may belong to an elevator adjoining the bridge. In addition, the engine room is described as being "hexagonal", while in the game,<ref name="for274">'''Halo: The Fall of Reach''', ''page 274''</ref> it consists of two vaguely rectangular chambers with the engine core in the middle. In the ''Combat Evolved'' level ''The Maw'', it is stated that the ''Pillar of Autumn'' has four fusion reactors, each of which is destroyed by the player; in ''The Fall of Reach'', the ship is also said to have a single main reactor nestled within two smaller reactor rings.{{Ref/Reuse|for274}} The ship is also described as having rotating centrifuges to generate [[artificial gravity]];{{Ref/Reuse|for274}} no rotating sections are present in the game, unless they are located within the hull.

*In the Tor 2010 reprint of ''The Fall of Reach'', Halsey's comment said in 2552 about Elites being a new species is edited, to reflect retcons that had them deployed since the beginning of the war. However, later on she states that "ONI hypothesizes at least two additional castes [which include] a warrior capable of commanding ground forces and possibly piloting their ships..."<ref>'''Halo: The Fall of Reach''', ''page 281'''</ref> In the original 2001 print, this statement referred to Elites, but can't in the reprint due to them not being merely theorized anymore. It is possible Halsey may be referring to [[Jiralhanae|Brutes]], but the Brutes too have been retconned to have been deployed at the war's start, with both Halsey's journal and the following reprint of ''First Strike'' confirming that they were encountered well before 2552.

*In ''Halo: The Fall of Reach'', when Captain Keyes awakens from cryo, Cortana informs him that the capacitors of the Pillar of Autumn's MAC gun are depolarized and the gun cannot fire,<ref>'''Halo: The Fall of Reach''', ''page 337''</ref> yet the gun is apparently used, and the loss of fire control is treated as a significant development in ''Halo: Combat Evolved'''s opening cutscene.
**It is possible that the crew managed to get the gun working again before the battle.

*The [[ONI Directorate Memorandum Interrogation Findings]] log included in the Adjunct section of the 2010 edition of ''Halo: The Fall of Reach'' refers to [[Preston Cole]] as a fleet admiral. Though there is a conflict over Cole's rank between ''Halo Wars: Genesis'' and ''The Impossible Life and Death of Preston J. Cole'' (see [[List of inconsistencies in the Halo series#The Impossible Life and the Possible Death of Preston J. Cole|here]]), no other source has referred to him as a fleet admiral.

*In order to destroy the RSO ''Fermion'', Chief Petty Officer McRobb saturated the station's fusion reactor chamber with deuterium. However, basic physics would dictate that such a method would not work. In fact, it is impossible to cause a fusion reactor to explode in real life by design.

===''Halo: Combat Evolved''===
{{Main|Halo: Combat Evolved}}

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*The main view screen on the {{UNSCShip|Pillar of Autumn}} labels the yet unidentified ring as "[[Installation 04|Halo]]". The name of the ring is not discovered until the level ''[[The Truth and Reconciliation]]''. This mistake is repeated in ''Halo: Combat Evolved Anniversary''.
*Cortana says she cannot begin to calculate Halo's pulse range just after [[343 Guilty Spark]] finishes telling her it has a radius of 25,000 light years.
**This can be accounted for by Cortana's inherent distrust of Guilty Spark's motives. Additionally, since Cortana is an [[Smart AI|AI]] with an insatiable urge to know everything she can, she may have tried to calculate the range herself regardless of whatever 343 Guilty Spark had told her.
*Almost every Pelican dropship bears the marking "[[Echo 419|E419]]", on its side, despite the fact that each Pelican has a different serial number.
**There is no canon explanation. This is due to only two Pelican textures, [[Victor 933|V933]] and E419, being used to represent every Pelican in the game.
*During the Warthog Run portion of ''The Maw'', the player has to travel a direct distance of over three kilometers atop the ''Pillar of Autumn'' to reach the [[GA-TL1 Longsword|Longsword]] fighter, but the ''Autumn'' is only 1.17 kilometers long.<ref>[http://halo.bungie.org/misc/sloftus_poaconundrum/images/POA-Full-Int-Ext.jpg '''Halo.Bungie.org''': ''Pillar of Autumn'']</ref> The Longsword's launch bay is also at the end of the Warthog run. The front or rear of a ship is an unlikely place to store a launch bay, which implies that the Master Chief traveled from side to side, further straining the realism of the sequence.
*During the level ''[[Assault on the Control Room]]'', [[Staff Sergeant]] [[Avery Johnson|Johnson]] can be seen with the Master Chief at the time he was really with [[Jacob Keyes|Captain Keyes]] searching for the Covenant's [[Flood containment facility|"weapon cache"]]; even though the Captain has been out of reach since [[The Silent Cartographer]].
**This is a result of [[Bungie]] reusing the "Johnson" NPC instead of creating another sergeant model. The same can be said for [[Marcus Stacker|Gunnery Sergeant Stacker]], who was treated as a generic NPC until ''Halo 4'', when he was finally explicitly identified in gameplay.
*In ''[[343 Guilty Spark (level)|343 Guilty Spark]]'' a body collapses on the Master Chief in the room where the [[Flood]] is introduced. It is unclear as to why this Marine was not infected when the Flood overran the personnel in the room.
** From an out-of-universe perspective, it's possible the Flood were not meant to infect dead bodies, but only take live hosts during the writing of ''Combat Evolved''. The [[Paranoid Marine]] may mention that he escaped the Flood by playing dead, a tactic that would not work after ''Halo 3'', where the Flood are witnessed infecting dead bodies.

===''Halo: Combat Evolved'' manual===
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*The ''[[Halo: Combat Evolved]]'' manual states that the [[Harvest]] [[First Battle of Harvest|incident]] took place in 2520.<ref>''[[Halo: Combat Evolved]]'' manual, page 4</ref> ''Halo: The Fall of Reach'' and all subsequent media unanimously place the attack in 2525.<ref>'''Halo: The Fall of Reach''', page 96</ref>
*The manual states that [[Jacob Keyes|Captain Keyes]] has served in the UNSC since 2526,<ref>''Halo: Combat Evolved'' manual, page 8</ref> though ''The Fall of Reach'' clearly states that he had recently graduated from OCS in 2517.<ref>'''Halo: The Fall of Reach''', page 19</ref>
*According to the manual, the Covenant attacked Reach two days before the Spartans' [[Operation: RED FLAG|mission to capture a Prophet]] was to begin. This is contradicted in ''Halo: The Fall of Reach'' and ''First Strike'', in both of which the ''Pillar of Autumn'' is already departing for the mission when the Covenant attack.
*The manual refers to the {{UNSCShip|Meriwether Lewis}} as a colony ship. The ship is said to be a frigate in ''Halo: The Fall of Reach''.<ref>'''Halo: The Fall of Reach''', ''page 139''</ref>

===''Halo: The Flood''===
{{Main|Halo: The Flood}}

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*In ''Halo: The Fall of Reach'', [[Lieutenant (UNSC)|Lieutenants]] [[Hall]] and [[Dominique]] are introduced as members of the command crew of the ''Pillar of Autumn'',<ref>'''Halo: The Fall of Reach''', ''page 300''</ref> but are absent in ''Halo: The Flood'' when the ship arrives at Installation 04.<ref>'''Halo: The Flood'''</ref>

*On page 3 of ''Halo: The Flood'', [[Thom Shephard]] tells [[Sam Marcus]] that they are resuscitating [[John-117]] before the ''Pillar of Autumn'' exits slipspace. However, in ''Halo: Combat Evolved'' Captain Keyes orders that John-117 be taken out of cryo after the ''Autumn'' is seen drifting in space and is preparing to be overrun by the Covenant.

*In ''Halo: The Flood'', the presence of the Covenant at Installation 04 is considered unrelated to the arrival of the ''Pillar of Autumn''; the Covenant are surprised by the arrival of the human ship and act as if it ended up in the system by either following one of their ships,<ref>'''Halo: The Flood''', ''page 5''</ref> or by chance.<ref>'''Halo: The Flood''', ''page 6''</ref> However, ''Halo: Combat Evolved'', ''Halo 2'' and the Covenant broadcast log featured in the Adjunct section in the 2010 reissue on ''The Flood'', state that the Covenant found the ring specifically by following the ''Autumn'''s slipspace jump from Reach, and arrived at the system in advance, waiting for the ''Autumn'' on the far side of Threshold.<ref>'''Halo: Combat Evolved''', campaign level ''[[The Pillar of Autumn (Halo: Combat Evolved level)|The Pillar of Autumn]]''</ref><ref>'''Halo 2''', campaign level ''[[The Heretic]]'': (Thel 'Vadam: ''"It fled, as we set fire to their planet. But I followed with all the ships in my command"'')</ref>

*In ''Halo: The Flood'', Cortana identifies [[Installation 04]] as "Halo" when escaping the ''Pillar of Autumn'',<ref>'''Halo: The Flood (2003)''', ''page 38''</ref><ref>'''Halo: The Flood (2010)''', ''page 50''</ref> but in ''Halo: Combat Evolved'', it is not identified by this name until the level [[Truth and Reconciliation (level)|Truth and Reconciliation]], when Captain Keyes mentions overhearing the name from his Covenant captors.

*According to ''Halo: The Flood'', there was an ocean at the bottom of the desert plateau the ''[[Truth and Reconciliation]]'' was holding position on.<ref>'''Halo: The Flood''', ''page 101''</ref> However, in both ''Halo: Combat Evolved'' and ''Halo: Combat Evolved Anniversary'', there is only solid ground below the plateau.

*In the ''Halo: Combat Evolved'' level ''[[Halo (Halo: Combat Evolved level)|Halo]]'', Cortana mentions that the survivors rescued by John-117 would be transported to the "[[command shuttle]]". The command shuttle is not mentioned in ''Halo: The Flood'', where [[Alpha Base]] serves as the main command post for UNSC forces.

*In ''Halo: Combat Evolved'', Cortana accesses Installation 04's Control Center by having the Master Chief remove her memory chip from his helmet and place it in the console. In ''Halo: The Flood'', she broadcasts herself into the system using the suit's transmitter.<ref>'''Halo: The Flood (2003)''', ''page 192''</ref><ref>'''Halo: The Flood (2010)''', ''page 209''</ref>

*There are several differences between ''Halo: The Flood'' and the ''Halo: Combat Evolved'' level ''[[The Maw]]'' in the encounter at the final service elevator on the ''Pillar of Autumn''. In ''Halo: The Flood'', [[Zuka 'Zamamee]] confronts John-117 by using a [[Type-29 Anti-Infantry Stationary Gun|Shade turret]], accompanied by several Grunts. Cortana takes control of the elevator and causes it to descend, allowing John-117 to drop in a pair of grenades and take out the Covenant.<ref>'''Halo: The Flood''', ''page 334-335''</ref> In the game, Cortana does not move the elevator and there are two Special Operations Elites and no Shade turret aboard.

*In ''Halo: The Flood'', many of the Marines John-117 fought alongside were female, despite no female Marines being in ''Halo: Combat Evolved'' at all. The Doylist explanation for this could easily be that there were only male marines modeled and voice-acted, and we should not take it as canon that there were no female marines on Installation 04. 

*In ''Halo: The Flood'', [[Stacker|Sergeant Stacker]] is not mentioned at any point, despite him being present on several occasions in the game. He is replaced during the raid on the ''[[Truth and Reconciliation]]'' by Sergeant Parker, and for the raid on the [[Silent Cartographer]] by Gunnery Sergeant [[Waller]]. One place where he might make an appearance is when the Chief rescued a crashed Marine squad with an unnamed Sergeant, where Stacker is normally found in the game.

*Throughout ''Halo: The Flood'', the Master Chief's or other characters' weapon loadouts at a given situation occasionally differ from those in the game. Stocks of ammo left behind by dead marines are not mentioned either.
**In Chapter 4, during the raid on the ''[[Truth and Reconciliation]]'', the novel illustrates that John ran out of ammo for his MA5B Assault Rifle, switching to an M6D pistol;<ref>'''Halo: The Flood (2003)''', ''page 112''</ref><ref>'''Halo: The Flood (2010)''', ''page 127''</ref> in the game, there are no pistols on that level at all.
*Also in Chapter 4, it is stated that "the Spartan was carrying a full combat load of ammo, grenades, and other gear, plus two magazines for the M19 launchers".<ref>'''Halo: The Flood (2003)''', ''page 101''</ref><ref>'''Halo: The Flood (2010)''', ''page 116''</ref> In the game, the Master Chief was not carrying a rocket launcher nor any magazines for it at the time.
*The novel consistently describes Marines wielding rocket launchers; no marines are ever seen wielding rocket launchers in the game. 
**This is due to in-game constraints, as is the inability for marines to drive Warthogs.

*As revealed in later sources, the Covenant has revered Forerunner AIs as "Oracles" for a long time,<ref>'''Halo: Contact Harvest''', ''page 272''</ref> but in ''Halo: The Flood'', 343 Guilty Spark was regarded as an enemy by the Sangheili.<ref>'''Halo: The Flood''', ''page 319''</ref> 
**This is probably because the fiction regarding the Covenant's beliefs had not yet been cemented by the time ''The Flood'' was written.

*[[Antonio Silva|Major Silva]] states intimate knowledge of the Spartan II program, specifically the child abductions,<ref>'''Halo: The Flood (2003)''', ''page 91''</ref> despite such details being strictly confidential. A Major in the ODST branch would certainly not have access to such information, nor toss it out so casually for no better purpose than to insult a Spartan.

===''Halo: First Strike''===
{{Main|Halo: First Strike}}

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In Chapter 33, it is said that Will and Linda went out to secure the area. It then says that the Master Chief climbed up to where Fred and Linda perched. Immediately after it says that Fred and Grace disembarked the dropship implying that Fred was still in the dropship and it is presumed that it was meant to say Will and Linda.<ref>'''Halo: First Strike''', ''page 303-304'' (2003 edition); ''page 365'' (2010 edition)</ref>

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*Prior to colliding in the launch bay of Ascendant Justice, the Longsword is going at a speed of 300&nbsp;m/s. This is equivalent to 1080&nbsp;km/h (671&nbsp;mph) and a sudden stop at that speed would kill the occupants immediately because of whiplash.<ref>'''Halo: First Strike''', ''Chapter 6''</ref>
** This is likely a typo with the correct value being 30&nbsp;m/s. Strangely, this has not been corrected in the Definitive Edition.

*John-117 notes that ''[[Ascendant Justice]]'' was the largest Covenant ship he had ever seen with its length of three kilometers.<ref>'''[[Halo: First Strike]]''', ''page 36'' (2003), ''page 52'' (2010)</ref> However, several staple Covenant ship types the Master Chief had encountered over his career, such as the {{Class|CAS|assault carrier}}, are significantly larger than the ''Ascendant Justice''<nowiki>'</nowiki>s described size.
**This is likely because the larger Covenant ship classes such as the CAS had yet to be introduced at the time of the novel's writing, although the error remains in the 2010 reissue.

*In ''Halo: Combat Evolved'', the Master Chief throws Private Jenkins' recorder chip away, but he still has it in ''First Strike''. This could be explained by the Chief's suit automatically making a copy of Jenkins' recording as a possible means of gathering intelligence, although this is only a theory.

*It is stated in ''Halo: First Strike'' that Dr. Halsey always referred to John by name, and never by rank or serial number.<ref>'''[[Halo: First Strike]]''', ''page 189'' (2003)</ref> However, in ''Halo: The Fall of Reach'', she called him "Master Chief" repeatedly.<ref>'''[[Halo: The Fall of Reach]]''', ''pages 225, 247, 253, and others''</ref>

*[[Frederic-104]] fires three shots from a [[Wraith]]'s [[plasma mortar]] which are powerful enough to reduce at least two [[Scarab]]s as well as nearby Covenant mining equipment to "piles of half-melted junk".<ref>'''Halo: First Strike''', ''page 143'' (2010)</ref> While the Scarabs were not named as such in the original edition (being only referred to as "insectlike diggers" and "giant insectlike machines"), the 2010 reissue's identification of the vehicles raises an inconsistency regarding their durability; in the games, Scarabs require sustained and concentrated fire to their weak points to take down, making the Wraith's mortar in the novel disproportionately powerful.

*The city of [[Côte d'Azur]] is repeatedly referenced as if it were a planet;<ref>'''Halo: First Strike''', ''pages 130, 131, 197, 238'' (2003)</ref> this mistake is repeated in ''[[Halo: Ghosts of Onyx]]''.<ref>'''Halo: Ghosts of Onyx''', ''page 149''</ref> Although ''First Strike'' and ''Ghosts of Onyx'' clearly refer to the Côte d'Azur described in ''The Fall of Reach'', this confusion may have given rise to the introduction of the separate planet named [[Cote d'Azure]] in later media.

*During Chapter 33 of ''Halo: The Fall of Reach'', many Covenant ships are destroyed, but not before they can let loose their plasma torpedoes which then destroy UNSC orbital defense platforms.<ref>'''Halo: The Fall of Reach''', ''page 299'' (2001)</ref> However, during a space battle in ''Halo: First Strike'', plasma en route to a target merely dissipates as the originating ship and its magnetic controls are destroyed.<ref>'''Halo: First Strike''', ''page 266'' (2003)</ref>
**It is possible that the magnetic controls were not destroyed in the former instance, allowing the plasma to continue to its target.

*The [[Prophet of Truth]]'s description differs considerably from his visual appearances, presumably because the Prophets' appearance had not yet been decided upon when the novel was written. While written from an ostensibly Covenant point of view, Truth is described as an "it" instead of a he. Truth is also said to have sensor and respiratory apparatus like insect antennae in his headpiece as well as protruding eyes and a snout, the rest of his face remaining obscured. Strangely, the description remains unaltered in the 2010 Definitive Edition.<ref>'''Halo: First Strike''', ''page 266'' (2003); ''page 406'' (2010)</ref>

*The interrogation transcript featured in the Adjunct section of the 2010 edition of ''Halo: First Strike'' continuously refers to [[Frederic-104]] as a lieutenant by the start of the [[Battle of Earth]]. In ''Halo: Ghosts of Onyx'', [[Frederic-104]] is not promoted to the rank of Lieutenant, Junior Grade until the end of the [[Onyx Conflict]].<ref>'''Halo: Ghosts of Onyx''', ''page 367''</ref>

===''Halo 2''===
{{Main|Halo 2}}

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*In the cutscene ''[[Another Day at the Beach]]'', the UNSC forces that land near [[Hotel Zanzibar]] wear [[ODST armor]], reflecting the analogous scene from the [[Halo 2 E3 demo]]. When the Marines are encountered at the hotel during the level [[Outskirts]], they wear standard Marine BDUs. Also, the location of the crashed Pelican does not match its position in game.
**This is because ''Another Day at the Beach'' was cut from the game before release. The Marines from the crashed Pelican were likely switched to regular Marines later in the level's development.
*In the level ''[[Delta Halo]]'', seven dead ODSTs are strewn about quite far from the landing zone. However, ''[[UNSC In Amber Clad|In Amber Clad]]'' dropped only eleven SOEIVs in the opening cinematic. The Master Chief, the three ODSTs who land near him, the three killed near the intended landing zone, and the seven ODSTs means that fourteen SOEIVs should have been deployed. This is probably a deliberate reference to the number [[seven]]: 14=7x2.

===''Halo: Ghosts of Onyx''===
{{Main|Halo: Ghosts of Onyx}}

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*[[Kurt Ambrose]]'s rank was apparently lieutenant commander in [[2545]], as said in the prologue.<ref>'''Halo: Ghosts of Onyx''', ''page 13''</ref> However, he was still referred to as a lieutenant by [[2551]] later in the story.<ref>'''Halo: Ghosts of Onyx''', ''pages 103-105''</ref> In Chapter 13, he is referred to as a lieutenant and then lieutenant commander several lines later.<ref>'''Halo: Ghosts of Onyx''', ''page 122''</ref>

*CPO Mendez remarks that [[Tom-B292]] and [[Lucy-B091]] are ten years old in Chapter 9,<ref>'''Halo: Ghosts of Onyx''', ''page 92''</ref> which is set in August 2541.<ref>'''Halo: Ghosts of Onyx''', ''page 89''</ref> However, it is previously established that both of them are twelve during [[Operation: TORPEDO]] in [[2545|July 2545]],<ref>'''Halo: Ghosts of Onyx''', ''page 26''</ref> meaning that they would have been eight years old in 2541. It is possible that Mendez misspoke as a result of not remembering the specific age of every individual Spartan due to their large numbers and the age differences between them.

*In November 2552, Kurt states that the [[Deep Winter|previous Zone 67 AI]] sent him a message via a [[Slipspace COM launcher|slipspace probe]] "years ago",<ref>'''Halo: Ghosts of Onyx''', ''page 176''</ref> even though the incident to which he refers took place in February 2551, less than two years earlier.<ref>'''Halo: Ghosts of Onyx''', ''page 107''</ref> It is likely that he simply misspoke.

*Kurt states that the [[Onyx Sentinel]]s first appeared on the morning of September 21, 2552, with Dr. Halsey noting that this date coincides with the "activation" of [[Installation 04]].<ref>'''Halo: Ghosts of Onyx''', ''page 175''</ref> However, earlier in the novel the Sentinels are described as appearing on the morning of October 31,<ref>'''Halo: Ghosts of Onyx''', Chapters 12-13</ref> unless they had been previously active in [[Zone 67]] and Kurt learned this after the October 31 attack from [[Endless Summer]]'s transmissions. It should also be noted that Installation 04 was never actually activated; although John-117 inserted the [[Activation Index]] to [[the Core]], Cortana prevented the activation sequence from commencing. However, it can be assumed that this, or the related events on Installation 04, were enough to alert Onyx's Sentinels; they could not have been roused by the arming of the [[Halo Array]] from [[Installation 05]], as this did not occur until November 3, although the Halos' arming is mentioned as having started the countdown to the closing of Onyx's shield world portal.<ref>'''Halo: Ghosts of Onyx''', ''pages 311, 317''</ref>

*[[Ash-G099]] is once addressed as a private.<ref>'''Halo: Ghosts of Onyx''', ''page 254''</ref> Although the novel does not explicitly identify Gamma Company's branch of service, they (like the rest of the Spartan-IIIs) are heavily implied to be Navy (this is later confirmed in ''Halo: Glasslands'').<ref>'''Halo: Glasslands''', ''page 38''</ref> The rank of private does not exist in the Navy and would be atypically low for Ash given his role as [[Team Saber]]'s leader.

*The narrator mentions the "ancient feud" between the [[Sangheili]] and the [[Jiralhanae]] at the time of the [[Great Schism]].<ref>'''Halo: Ghosts of Onyx''', ''page 193''</ref> As it was later established, the Jiralhanae were discovered by the Covenant in [[2492]], which would hardly make the two species' feud "ancient".

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*It is stated that the [[MJOLNIR Mark IV]] armor has an AI interface port in a chapter set in [[2531]].<ref>'''Halo: Ghosts of Onyx''', ''page 37''</ref> The AI interface was not added to the Mjolnir system until the final model of the Mark V in 2552.<ref name="Halo page 252">'''Halo: The Fall of Reach''', ''page 252''</ref>

*The [[UNSC frigate|frigate]] {{UNSCShip|In Amber Clad}} is erroneously referred to as a [[UNSC destroyer|destroyer]].<ref>'''Halo: Ghosts of Onyx''', ''page 185''</ref>

*In ''Halo: First Strike'', Dr. Halsey puts four [[M7/Caseless Submachine Gun|submachine guns]] in a bag.<ref>'''Halo: First Strike''', ''page 273''</ref> In ''Halo: Ghosts of Onyx'', Kelly finds the same weapons, but they are four [[MA5B assault rifle]]s instead.<ref>'''Halo: Ghosts of Onyx''', ''page 161''</ref>

*In ''Halo: Ghosts of Onyx'', Kurt Ambrose remarks that some of the Alpha Company candidates were orphaned at [[Jericho VII]].<ref>'''Halo: Ghosts of Onyx''', ''page 70''</ref> His speech takes place on December 12, 2531, yet Jericho VII was not glassed until February 2535.<ref>'''Halo: The Fall of Reach''', ''Prologue''</ref>
**While this is most likely to be a simple oversight, it is possible that the candidates from Jericho VII were orphaned in a yet-unseen engagement that preceded the Covenant attack of 2535, as the background of the Covenant invasion of Jericho VII is not elaborated upon in ''The Fall of Reach''. For example, the events that occurred may have been similar to how the Covenant initially [[Battle of Arcadia|invaded Arcadia]] in 2531 but only arrived to [[Fall of Arcadia|glass the planet]] eighteen years later.

*Dr. Halsey notes that Kurt stands "nearly two and a half meters" tall in his SPI armor.<ref>'''Halo: Ghosts of Onyx''', ''page 173''</ref> This is suspect, as Kurt is never remarked as being unusually tall among the Spartan-IIs. [[Samuel-034]], by far the tallest of the Spartan-IIs, stood at 238.8 centimeters in his Mjolnir armor, while [[Jorge-052]] was noted to be unusually tall for a Spartan-II at his 223.5 centimeters in height.

*On page 129 of ''Halo: Ghosts of Onyx'', [[Franklin Mendez]] is mentioned to be "pushing sixty [years old]" in 2552, which implies that his birthdate is close to or after 2493; he is previously mentioned as having "aged well" in 2531. However, this would give him a maximum age of 24 when he started training the Spartan-IIs, which is unlikely given his description in ''Halo: The Fall of Reach'' as a grizzled veteran instructor who had seen much combat, as well as his high rank of [[Chief Petty Officer]], as of 2517.<ref>'''Halo: The Fall of Reach''', ''pages 28-29'' (2001)</ref> Additionally, because combat-oriented UNSC military personnel typically spend significant spans of time in cryosleep Mendez's biological age would likely be even less than his nominal one. [https://www.halowaypoint.com/en-us/universe/characters/chief-mendez Mendez's Halo Waypoint biography] establishes his date of birth as March 24, 2492, making him 60 years old at the time.

===''Halo 3''===
{{Main|Halo 3}}

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*Every Longsword fighter bears the marking ''7-89'' on its side, despite each Longsword canonically having a different serial number. This is the result of reusing the same model for all Longswords in the game.
*In the ending cutscene of the level ''[[The Storm]]'', all three UNSC frigates have the same serial number and all are labeled "''Forward Unto Dawn''". This is also obviously the result of reusing the same model.
*In the ending cutscene of the level [[Halo (Halo 3 level)|''Halo'']], the Arbiter is shown sitting at the bridge's helm after leaving the hangar. After the ''Dawn'' is cut in half by the portal, the Arbiter arrives on Earth in the front half of the ship, yet the bridge remains attached to the back half of the ship. Presumably the Arbiter moved toward the fore end just before the ship was bisected. However, the cutscene appears to occur in real time; thus, he would have had mere seconds to descend roughly two decks from the bridge to the main hull, after which he would have to move forward at least fifty meters to avoid being caught in the aft section.

===''Halo: Contact Harvest''===
{{Main|Halo: Contact Harvest}}

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*''Halo: The Fall of Reach'' states that Harvest has a population of three million. However, in ''Halo: Contact Harvest'', it is stated to have a little over 300,000. The figure presented in ''Contact Harvest'' has been ignored in later media, and the population is listed as three million in ''[[Halo: Fall of Reach - Boot Camp]]'' and ''[[Halo: The Essential Visual Guide]]''.

*Throughout ''Halo: Contact Harvest'', the [[Eridanus system|Eridanus]] and [[Epsilon Eridani system|Epsilon Eridani]] star systems are referenced as being one system: "Epsilon Eridanus". It is implied that both [[Reach]] and [[Eridanus II]] are situated in this system.<ref>'''Halo: Contact Harvest''', ''page 111''</ref> With two exceptions, (a chapter heading in the first printing of ''Halo: The Fall of Reach''{{Ref/Reuse|for81}} and the "Reclaimer" entry in the [[Bestiarum]]), the two systems are regarded as separate in all other fiction; in ''Halo: First Strike'', for instance, the main characters travel from Epsilon Eridani to Eridanus, a journey that would take days were it not for the [[Forerunner crystal]] from beneath [[CASTLE Base]].{{Ref/Reuse|fornumbers}}<ref>'''Halo: First Strike''', ''pages 242, 261''</ref>

*The [[Insurrection]] is described as being largely confined to the aforementioned "Epsilon Eridanus" system, whereas outer systems are described as being more stable due to their more homogeneous populaces.<ref>'''Halo: Contact Harvest''', ''page 61-62''</ref> In other media, the Insurrection is depicted as occurring almost exclusively in the Outer Colonies and spanning numerous star systems. Additionally, the highly varied populations of the Outer Colonies are cited as one of the reasons for their instability. Prior to ''Contact Harvest'', no mention was made of fighting breaking out in Epsilon Eridani; on the other hand, the conflict was described as being at its most active in the similarly named Eridanus system. This has been partly reconciled in later fiction, with the Insurrection being active in both systems, although the claim that the conflict at large was confined to Eridanus has been ignored.

*[[Operation: TREBUCHET]] is stated to be the name for the UNSC's entire ongoing campaign against the [[Insurrectionist]]s as of [[2524]].<ref>'''Halo: Contact Harvest''', ''page 11''</ref> This contradicts ''Halo: The Fall of Reach'', which establishes TREBUCHET as a single counterinsurgency operation against the rebels in the Eridanus system in [[2513]], one that is treated as an event long past by 2525.<ref>'''Halo: The Fall of Reach''', ''pages 75-76'' (2001)</ref> However, the [[Halo Wars Timeline Events|in-game timeline]] in ''[[Halo Wars]]'' refers to Operation: TREBUCHET as "upcoming" in an entry dated 2520;<ref name="hwtimeline">[[Halo Wars Timeline Events|'''Halo Wars''' — ''Timeline'']]</ref> furthermore, ''[[Halo: Mortal Dictata]]'' references TREBUCHET as the ''"last counterinsurgency operation against the colonies"'',<ref>'''Halo: Mortal Dictata''', ''page 94''</ref> lending more credence to the version presented in ''Contact Harvest''.

*In ''Halo: Contact Harvest'', humanity is said to have seventeen planetary colonies.<ref>'''Halo: Contact Harvest''', ''page 74''</ref> In a [http://forums.bungie.org/halo/archive28.pl?read=847733 forum post], [[Joseph Staten]] suggested that a large number of the colonies are smaller settlements or outposts; he admitted to being "intentionally vague" in order to leave room for possible future expansion. Later media have ignored Staten's claim, showing that the [[Unified Earth Government]] had at least several dozen developed colony planets and had some presence on over 800 worlds.

===''Halo: The Cole Protocol''===
{{Main|Halo: The Cole Protocol}}

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When [[Jacob Keyes|Lieutenant Keyes]] is warned of the incoming [[Covenant fleet]] and asks what UNSC ships are nearby, the book first states that three [[UNSC destroyer|destroyers]] are picketing, but immediately counters that the {{UNSCShip|Midsummer Night}} and three '''frigates''' would be unable to repel a Covenant assault.<ref>'''Halo: The Cole Protocol''', ''page 136''</ref> However, they are later confirmed to be destroyers, one of which is the {{UNSCShip|Do You Feel Lucky?}}.<ref>'''Halo: The Cole Protocol''', ''page 138''</ref>

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*According to ''Halo: The Flood'', Jacob Keyes killed his first human with a pistol which is specifically stated to have a barrel;<ref>'''Halo: The Flood''', ''page 198''</ref> however, ''Halo: The Cole Protocol'' states he used a modified {{Pattern|Okarda'phaa|plasma rifle}}, a weapon which lacks any form of barrel.<ref>'''Halo: The Cole Protocol''', ''page 129''</ref>

*Thel 'Vadam reacts to [[Jai-006]]'s face-concealing Mjolnir helmet with extreme disgust, believing that only a "soulless and dead" being would hide his face.<ref>'''Halo: The Cole Protocol''', ''page 275''</ref> This is uncharacteristically hypocritical in light of the fact that many [[Combat harness|Sangheili combat harness]] variants have helmets that fully cover the wearer's face; it is unlikely Thel would so harshly condemn something that is a common practice among his own kind.

*''The Cole Protocol'' establishes the notion that the Sangheili stigmatize doctors and medical treatment, a cultural trait that is echoed in later works. However, in ''Halo: The Flood'', [[Zuka 'Zamamee]] is treated by "medics" for wounds he received aboard ''Pillar of Autumn'' and this is never regarded as being something out of the ordinary, let alone disgraceful.<ref>'''Halo: The Flood''', ''page 61'' (2003 edition)</ref>

===''Halo Wars''===
{{Main|Halo Wars}}

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In the level ''[[Dome of Light]]'', after requesting the first [[Rhino]] to be deployed, the radio operator on the {{UNSCShip|Spirit of Fire}} will identify the player as "Harvest Surface Command" even though the level takes place on [[Arcadia]].
*This may be because ''Spirit of Fire'' was still assigned to Harvest.

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*Although the Forerunner [[Relic (location)|relic]] on Harvest is discussed by Captain Cutter and Professor Anders at the end of ''Halo Wars: Genesis'', its discovery is treated as new information in the game's opening cinematic. The simplest explanation is that Forge's discovery of the relic in the cutscene takes place during the events of ''Genesis''.
*In all renders and cutscenes, most notably "[http://www.youtube.com/watch?v=zV-m8kJCUI4 She Is Not My Girlfriend]" at the beginning of the level ''[[Anders' Signal]]'', the [[M41 Light Anti-Aircraft Gun]] is shown with four barrels. It is likely that this is a variant of the M41 LAAG, similar in design to the [[M41 Extended Light Anti-Aircraft Gun]] mounted on the [[Open Frame 92/Extra-Vehicular Activity|OF-92 Booster Frame]].

===''Halo 3: ODST''===
{{Main|Halo 3: ODST}}

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*The depiction of the city of [[New Mombasa]] in ''Halo 3: ODST'' differs significantly from its ''Halo 2'' incarnation, the most prominent changes being the replacement of the [[Mombasa Tether]] to a separate island and a major restructuring of the island's general shape. As a result, the [[Prophet of Regret]]'s assault carrier ''[[Solemn Penance]]'' is also moved to a different location over the city than it is in ''Halo 2''.

*In ''Halo 3: ODST'', ''Solemn Penance'' is stationary just before jumping into slipspace, yet in ''Halo 2'' during the closing cutscene of the level ''[[Metropolis (level)|Metropolis]]'', the assault carrier is moving forward.
**During the same scene in ''Halo 3: ODST'', the ''[[UNSC In Amber Clad|In Amber Clad]]'' is seen approaching the carrier in a straight line and is clearly separate when they jump, but in ''Halo 2'', the ''In Amber Clad'' flies in an arc to a position underneath the starboard side of the assault carrier. These changes were made for the sake of drama and to make the scene easier to witness from the [[Rookie]]'s point of view.

===''Halo: Helljumper''===
{{Main|Halo: Helljumper}}

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In the comic, [[Kojo Agu]] notes that [[Dutch]] makes a habit of never calling him by his nickname "Romeo" and instead by variants like "Romes". In ''Halo 3: ODST'' and ''Halo: New Blood'', Dutch always refers to him as Romeo. 

===''Halo Legends''===
{{Main|Halo Legends}} 

====''The Babysitter''====
{{Main|The Babysitter}}

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According to ''Halo: The Fall of Reach'', ONI's intelligence on the [[Prophet]]s as of the briefing for [[Operation: RED FLAG]] on August 27, 2552 was extremely scarce; their appearance was unknown and their existence was only inferred from Covenant communications.<ref>'''Halo: The Fall of Reach''', ''pages 276-278'' (2010)</ref> Debriefings and [[helmet recorder]] data from the [[Raid on Heian|mission]] depicted in ''The Babysitter'' (which can be inferred to have occurred prior to November 2551 due to the [[MJOLNIR Mark IV]] armor still being in service) would no doubt have shed more light into the appearance and role of the Prophets, which would in all likelihood have been utilized in the Spartans' RED FLAG briefing due to the mission's critical nature.
*This may be a retcon similar to later media ignoring the nature of the first human contacts with Sangheili, Jiralhanae and Mgalekgolo in ''The Fall of Reach'' and ''First Strike'', though the statements about the Prophets remain unchanged in the revised edition of ''The Fall of Reach''. This is probable since Linda-058 was deployed on a [[Operation: HORN AND HIDE|similar mission]] to assassinate a Prophet on [[Odenli'sh]] during the war.<ref>[https://www.halowaypoint.com/en-us/universe/characters/linda-058 '''Halo Waypoint:''' ''Linda-058'']</ref>

===''Halo: Evolutions - Essential Tales of the Halo Universe''===
{{Main|Halo: Evolutions - Essential Tales of the Halo Universe}}

====''Pariah''====
{{Main|Pariah}}

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Jacob Keyes is shown to be aware of the reason behind [[Catherine Halsey|Dr. Halsey]]'s mission to observe the [[SPARTAN-II program|Spartan-II]] candidates.<ref>'''Halo: Evolutions''', ''"[[Pariah]]"'', ''page 16''</ref> However, ''Halo: The Fall of Reach'' and [[Halsey's journal]] clearly indicate that Keyes was unaware of the mission's true nature, and that Halsey had him reassigned before he could find out.<ref>'''Halo: The Fall of Reach''', ''page 28'' (2001 edition)</ref> 

====''Stomping on the Heels of a Fuss''====
{{main|Stomping on the Heels of a Fuss}}

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[[Connor Brien]] is stated to have spent time on ''[[High Charity]]'' prior to the events on [[Beta Gabriel]]. However, evidence suggests that the UNSC had no knowledge of ''High Charity'' at this time. Brien was deployed to Beta Gabriel shortly following the [[Fall of Reach]] in August [[2552]]. In the ''Halo 2'' level [[Regret (Halo 2 level)|Regret]], which takes place on November 2, 2552, [[Cortana]] refers to the space station as "'''something called''' ''High Charity''", indicating that she is entirely unfamiliar with it or its role as the Covenant capital.<ref>'''Halo 2''', campaign level ''[[Regret (Halo 2 level)|Regret]]'': (Cortana: ''"I've intercepted a secure transmission from Regret's Carrier to the something called ''High Charity''."'')</ref> Cortana's previous mission was to be [[Operation: RED FLAG]], an [[Office of Naval Intelligence#Section Three|ONI Section III]]-initiated operation to locate and capture the Covenant's leadership. It is extremely unlikely that ONI would have chosen to withhold its knowledge of ''High Charity'' from her, given the supreme importance of RED FLAG.

====''The Mona Lisa''====
{{Main|The Mona Lisa}}

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It is repeatedly stated that the UNSC has a policy not to take Covenant prisoners and the main characters are baffled when they discover Covenant prisoners aboard the prison vessel ''[[Mona Lisa]]''.<ref>'''Halo: Evolutions''', ''"The Mona Lisa"'', ''pages 262, 269''</ref> However, UNSC personnel are shown taking Covenant prisoners in ''Halo: The Flood'', ''Halo Wars: Genesis'', and several later sources. It is likely that the "policy" to which the characters refer is a guideline or standard operating procedure rather than an official protocol.

====''Palace Hotel''====
{{Main|Palace Hotel (short story)}}

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The specifics of the events of the ground battle in [[New Mombasa]] differ significantly between the ''Halo 2'' level ''[[Metropolis]]'' and the ''Halo: Evolutions'' story ''[[Palace Hotel]]''. In addition to extensive changes in dialog, several events and locations are described differently. For example, the scene in the parking lot of the [[Kilindini Park Cultural Center]], featured in ''Palace Hotel'', is not present in the game. The ending of ''Palace Hotel'' is also different from ''Metropolis'', where John makes his way to a Marine outpost in a [[Mtangulizi Kampuni|corporate]] building instead of a [[Palace Hotel (location)|hotel]]. In the game, it is mentioned that the Marines' lieutenant was killed as soon as they arrived and that [[Banks|Sergeant Banks]] is in charge at the time, while in ''Palace Hotel'', John meets the Marines' [[Parisa|lieutenant]] at the outpost. Overall, ''Palace Hotel'' could be regarded as an alternate-continuity take on the story as presented in ''Halo 2'', much as the ''Fall of Reach'' comic series is an alternate incarnation of the novel's story.

====''Human Weakness''====
{{Main|Human Weakness}}

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[[Cortana]] knows about the death of [[Colonel]] [[James Ackerson]] while being held captive by the [[Gravemind]] on ''High Charity''.<ref>'''Halo: Evolutions - Essential Tales of the Halo Universe''', "[[Human Weakness]]", ''page 387''</ref> However, the scene takes place days prior to Ackerson's death after the [[Battle of Cleveland]] sometime between November 8 and 17.<ref>'''Halo: Uprising''', [[Halo: Uprising Issue 4|Issue #4]]''</ref>

====''The Impossible Life and the Possible Death of Preston J. Cole''====
{{Main|The Impossible Life and the Possible Death of Preston J. Cole}}

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*[[Preston Jeremiah Cole|Vice Admiral Preston Cole]] is said to have had 117 ships under his command during the [[Battle of Alpha Aurigae]]. ''[[Halo Wars: Genesis]]'' states he had 107 ships in the same battle.

*According to the story, two of Preston Cole's great-grandfathers served in the [[Rainforest Wars]].<ref>'''Halo: Evolutions -  Essential Tales of the Halo Universe''', ''"The Impossible Life and the Possible Death of Preston J. Cole"'', ''page 415''</ref> However, the conflict took place more than three centuries before Cole's birth.
**Cole's ancestors may instead have served in the ill-defined [[Inner Colony Wars]].

*There are multiple discrepancies involving [[Michael Stanforth|Admiral Stanforth]]'s name, age and rank; for a more detailed analysis, see [[Michael Stanforth#Discrepancies|here]].

*In ''Halo Wars: Genesis'',  the ''Halo Wars'' in-game timeline, and the pre-release timeline for ''Halo: Combat Evolved'', Preston Cole is said to have been promoted to full admiral after his [[Second Battle of Harvest|victory at Harvest]]. In ''The Impossible Life and the Possible Death of Preston J. Cole'', no mention is made of his promotion and he is referred to as a vice admiral throughout the story, even as late as his final broadcast in the [[Battle of Psi Serpentis]] in [[2543]]; ''[[Halo: The Essential Visual Guide]]'' also refers to him as a vice admiral. It is possible his rank expired or he may have been demoted in an unseen event.
**The [[ONI memorial]] in ''Halo 3: ODST'' refers to Cole posthumously as a full admiral. However, the memorial is not a wholly reliable source given several other canonical inconsistencies with established media.

*The ''CCS''-class battlecruiser is said to have first been encountered at the Battle of Psi Serpentis in 2543. This contradicts ''Halo Wars: Genesis'', which shows Cole's fleet engaging such vessels in [[2526]]; ''Halo Wars'', in which two ''CCS''-class ships are encountered and identified as such at Arcadia in 2531; [[Data pads|data pad 10]], which states that the [[The Assembly|Assembly]]'s findings about glassing were derived from observing the ''CCS'' class in 2526; and ''Halo: The Essential Visual Guide'' and the ''Halo Encyclopedia: The Definitive Guide to the Halo Universe'', which state that vessels of the class were encountered frequently throughout the war.

*In reference to the [[Reach super-AI network]], Cole states, ''"They're the only ones in the Outer Colonies with the raw power to get the job done."''<ref>'''Halo: Evolutions - Essential Tales of the Halo Universe''', "The Impossible Life and the Possible Death of Preston J. Cole", ''pages 475-476''</ref> However, Reach is the most significant of the extrasolar [[Inner Colonies]].

====''Soma the Painter''====
{{Main|Soma the Painter}}
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The [[Auditor]] and the [[Prelate (Forerunner)|Prelate]] agree to inform the [[Ur-Didact|Didact]] of the Flood's appearance at [[Seaward]].<ref>''Halo: Evolutions Volume II'', page 10</ref> However, ''[[Halo: Cryptum]]'' reveals that the Didact was in exile on Earth at the time and would not be revived from [[Cryptum|suspended animation]] until nearly three centuries after the events of the short story.

===''Halo: Blood Line''===
{{Main|Halo: Blood Line}}

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The [[smart AI]] [[Iona]] interfaces with [[Victor-101]] through his [[neural interface]], even using the system to force some of his memories to resurface, indicating that he has received the [[Spartan neural interface]] upgrade allowing such connectivity. The comic series is set prior to the finale of the [[Fall of Reach]], indicating that Victor must have received the upgrade some time earlier. According to ''Halo: The Fall of Reach'' and a Bungie Weekly Update,<ref>[http://halo.bungie.net/News/content.aspx?type=topnews&link=BWU_012910 '''Bungie.net''': ''Bungie Weekly Update, 1/29/10'']</ref> [[John-117]] was the first Spartan to receive the upgrade and neurally integrate with a smart AI on [[2552#August|August 29, 2552]]; this is later corroborated by the [[data pads]] of ''Halo: Reach'', in which the [[The Assembly|Assembly]] makes note of the melding of John's and Cortana's neural networks as a monumental achievement in their own goals.<ref>'''[[Halo: Reach]]''', ''[[Data pads|Data pad 18]]''</ref>

===''Halo: Reach''===
{{Main|Halo: Reach}}

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*During the level "[[Long Night of Solace (level)|Long Night of Solace]]", [[Urban Holland|Colonel Holland]] once refers to the [[Ceudar-pattern heavy corvette|Covenant corvette]] ''[[Ardent Prayer]]'' as a cruiser.<ref>'''Halo: Reach''', campaign level ''[[Long Night of Solace (level)|Long Night of Solace]]'' (''"Find a way inside, and permanently disable the cruiser's communications."'')</ref>

*In the game's introductory cinematic, the Covenant-conquered [[Reach]] is depicted as being [[:File:Reach Glassed.jpg|only partially glassed]]; the [[data pads]] in the game explain the impossibility of the Covenant fully glassing a planet's surface, supported by statements of a similar nature in [[Dr. Halsey's personal journal]]; additionally, references to the complete glassing of Reach were modified in the 2010 reissue of ''[[Halo: First Strike]]''. However, in the skybox of the multiplayer map "[[Condemned]]", Reach's surface is depicted as being [[:File:Reachglassed.png|almost completely ablaze]], significantly different from the more subdued imagery in the game's introduction. This discrepancy may stem from the map having been created by a separate studio, [[Certain Affinity]], who may not have been properly informed of the wider retcon regarding the Covenant's glassing capabilities or the specific instance of Reach's glassing.

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*In ''Halo: Combat Evolved'' and ''Halo: The Flood'', which take place directly after ''Halo: Reach'', the Marines on board the ''Pillar of Autumn'' are armed with MA5B assault rifles. However, in ''Reach'', the Marines assigned to the ''Pillar of Autumn'' are armed with MA37 assault rifles.
**From a game design perspective, this is due to Bungie declining to spend resources to create a weapon that would already have its place in the "sandbox" filled, especially given the relatively brief appearance it would make. From a canon perspective, it has since been explained that Marines will utilize Army weaponry should the situation require, as occurs in ''Halo: Reach''.<ref>[http://halo.xbox.com/forums/games/f/5/p/7250/70316.aspx#70316 '''Halo Waypoint Forums''': ''The UNSC Army discrepancy in CE can be fixed]''</ref>

*According to an [[Intersystem News]] sheet that comes with the [[Halo: Reach Limited Edition|Limited]] and [[Halo: Reach Legendary Edition|Legendary]] editions of the game, Jacob Keyes was already a captain in [[2550]]. However, according to ''Halo: The Fall of Reach'', he was not promoted to captain until after he performed the famous [[Keyes Loop]] in [[2552#July|July 2552]].<ref>'''Halo: The Fall of Reach''', ''page 161'' (2001 edition)</ref>
**This could be an in-universe research error.

*''Halo: Reach'' places [[Olympic Tower]] in the city of [[New Alexandria (location)|New Alexandria]]. ''Halo: The Fall of Reach'' states that the building was part of Reach's [[Fleet Command Headquarters]],<ref>'''Halo: The Fall of Reach''', ''page 230'' (2001)</ref> which is implied by ''The Fall of Reach'' and ''First Strike'' to be located within the [[Reach FLEETCOM Military Complex]] in the [[Highland Mountains]] as opposed to a civilian city. ''Halo: Reach'' also gives no indication that Olympic Tower is part of a larger FLEETCOM complex. Additionally, the game depicts New Alexandria's conquest and glassing on August 23; the FLEETCOM HQ was still intact as of August 30 in ''The Fall of Reach'', as the book has the Covenant launch an overwhelming ground assault to take the HQ.<ref>'''Halo: The Fall of Reach''', ''page 300'' (2001)</ref>

*The placement of the multiplayer map "[[Breakneck]]" in New Mombasa is inconsistent with the city's ''Halo 3: ODST'' incarnation. Assuming the locations of the city's landmarks, such as the bridge of the [[Uplift Nature Reserve]], are consistent with ''ODST'', the map should be situated near the southernmost main section of the Reserve. No skyscrapers or streets are present in the area in ''ODST''.<ref>[[:File:Uplift rings.jpg]]</ref> In addition, according to the player's HUD compass, the city center and the Mombasa tether are situated to the south and southwest of the map, respectively. Based on the way the city is presented in ''ODST'', the aforementioned landmarks would be located to the north and northwest of the Uplift Reserve and thus the map's playable area.

*While stated to be set on Installation 04,<ref>[http://blogs.halowaypoint.com/Headlines/post/2011/11/09/The-Halo-Bulletin-11911-.aspx '''Halo Waypoint''': ''The Halo Bulletin: 11/9/11'']</ref> the skybox of the map "[[Ridgeline]]" features a prominent Earth-like world with visible continents and oceans as opposed to the gas giant [[Threshold]].

*In [[Data pads#Legendary difficulty|Data Pad 14]], [[the Assembly]] claims that only eight human colonies ([[Harvest]], [[Green Hills]], [[Second Base]], [[Bliss]], [[Madrigal]], [[Chi Ceti system|X Ceti]], [[Cote d'Azure]], and [[Asmara]]) had been glassed by the start of [[2530]]. However, additional media has established that numerous other colonies had been glassed by this point, including [[Biko]],<ref name="tug">''Halo: First Strike'' (2010), "Tug o' War"</ref> [[Circinius IV]],<ref>'''Halo 4: Forward Unto Dawn''', ''Episode 5''</ref> and [[Etalan]],{{Ref/Novel|Id=HSS9|HSS|Chapter=9}} As the data pads are in-universe documentation, they are as prone to errors as real-world documents and it is possible that the Assembly was unaware that these colonies had been glassed, even if they were known to have been lost.

===''Halo: Fall of Reach''===
{{Main|Halo: Fall of Reach}}

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* When the Spartans are issued their original Mjolnir armor the plating is free of any markings. All subsequent panels show the Spartans' tags on their chestplates.
* When Halsey puts on John's helmet for him, the helmet in her hands resembles the Mark VI's, with its raised brow, oval visor groove, and square mouth guard. In the next panel it is now the Mark IV helmet, with its lowered brow, sleeker shape, and large breathing ports.
** The bonus layout artwork for ''Covenant'' shows the Spartans wearing the Mark VI-style armor from "The Package" in the initial sketches, though it is changed to ''Halo Wars''-style Mark IV armor before the inking and coloring. It may be that the Mark VI in Halsey's hands is likewise an error that was missed in the correcting phase.
* During the skirmish between the ''Unrelenting'' and the {{UNSCShip|Commonwealth}}, Captain Wallace orders for a Shiva nuke to be fired at the Covenant ship and for their MAC to be fired. Just as the nuke is launched, a bridge officer confirms the ''Commonwealth'' MAC has charged to 100%. The nuke impacts the ''Unrelenting'', dropping its shield and causing some damage near the bow, but the MAC is never seen being fired or impacting.
* When Blue Team struggles with opening the door leading inside the ''Unrelenting'', they appear to still be in vacuum. However, a Jackal without any breathing gear fights them after the door opens.
** In the book, the first door to the interior of ''Unrelenting'' opened automatically, then shut to restore the atmosphere, with the second one having to be manually opened. The comic appears to have skipped the previous door and a comment from Kelly about the size of the door implies that it is the first one they encountered.
* When the Spartans are briefed about Operation: RED FLAG, Halsey reports ONI has just discovered a new Covenant species, the Prophets, and shows an image of the Prophet of Truth. Yet in an earlier issue, taking place in 2525, the Spartans, Halsey, and Vice Admiral Stanforth watch a broadcast from the Prophet of Regret himself, who displays his image quite visibly.

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''Halo: Fall of Reach'' departs from the source novel in numerous instances, with many liberties taken to better suit the comic medium. As it is not a particularly strict adaptation of the novel, one may regard it as an alternate interpretation of the original story, as opposed to an unintentionally contradictory narrative or a retcon. For a list of differences between the novel and the comic adaptation, see [[List of changes in Halo: The Fall of Reach rereleases|here]].

===''Halo: Cryptum''===
{{Main|Halo: Cryptum}}

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*[[Bornstellar]] concludes that the device used to camouflage the central island of [[Djamonkin Crater]] must be a [[baffler]] instead of a [[dazzler]] after witnessing its effects.<ref>'''Halo: Cryptum''', ''page 43''</ref> However, he later refers to it as a dazzler.<ref>'''Halo: Cryptum''', ''pages 51, 53''</ref>

*The [[Librarian]] is said to be older than the [[Ur-Didact|Didact]] at "over eleven thousand years" of age,<ref>'''Halo: Cryptum''', ''page 338''</ref> yet previously the Didact is mentioned to have served as [[protector of the ecumene]] for twelve thousand years.<ref>'''Halo: Cryptum''', ''page 233''</ref>

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Six Halos are described holding station over one of the [[Ark]]s,<ref>'''Halo: Cryptum''', ''page 329'' (''"Slowly it dawned on me that I was looking upon another array of installations: six rings, each rising from one of the petals of an enormous flower."'')</ref> which ''[[Halo: Silentium]]'' establishes as the [[greater Ark]]. However, ''Silentium'' clarifies that the newer array of six Halos was manufactured by (and hidden at) the lesser Ark.<ref>'''Halo: Silentium''', ''page 237''</ref> There is no apparent reason for the six rings (the Forerunners' carefully guarded last resort) being temporarily transported to the greater Ark.

===''Halo: Glasslands''===
{{Main|Halo: Glasslands}}

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*At the conclusion of ''Halo: Ghosts of Onyx'', Onyx dissolves into trillions of [[Onyx Sentinel|Sentinels]] that vaporize any vessels nearby and remain to guard the slipspace rift to the [[Trevelyan|shield world]] formerly in the core of the planet.<ref>'''Halo: Ghosts of Onyx''', ''page 378''</ref> These Sentinels are wholly absent in ''Glasslands'', in which UNSC vessels are capable of traversing the former site of [[Onyx]], now said to contain a debris field, without any sign of threat.<ref name="glass47">'''Halo: Glasslands''', ''pages 47-48''</ref> While the Onyx Sentinels are mentioned in passing when referencing the events of ''Ghosts of Onyx'',{{Ref/Reuse|glass285}} their disappearance is neither noted nor explained.

*[[Lieutenant Commander]] [[Kurt Ambrose]] is referred to as "Lieutenant" Ambrose.{{Ref/Reuse|glass47}}

*[[Margaret Parangosky|Admiral Parangosky]] states that [[Catherine Halsey|Dr. Halsey]] escaped with "billions of dollars' worth of UNSC resources".<ref>'''Halo: Glasslands''', ''page 49''</ref> The reference to dollars is out of place, as the [[credit]] is the standard currency within the UEG; previously, for example, a reference to "dollars" in a contemporary setting was retconned to "credits" in the 2010 reissue of ''Halo: The Fall of Reach''.<ref>'''Halo: The Fall of Reach''', ''page 232'' (2001 edition)</ref><ref>'''Halo: The Fall of Reach''', ''page 264'' (2010 edition)</ref>

*During one of her briefings to Kilo-Five, Captain [[Serin Osman]] operates under the presumption that the existence of Onyx, as well as Parangosky's cover-up of the planet, should be common knowledge. None of the members of Kilo-Five shows any indication that they were unaware of the planet beforehand.<ref name="glass285">'''Halo: Glasslands''', ''page 285''</ref> Onyx was removed from all navigation charts and databases in 2511,<ref>'''Halo: Ghosts of Onyx''', ''page 124''</ref> before most members of Kilo-Five were born. As such, the rest of Kilo-Five, apart from Osman and Black-Box, would have no way of knowing that a planet called Onyx existed in the first place, much less that Parangosky had classified it. While it is possible that some information about the planet did leak out to the public (as suggested in ''[[Halo Wars: Genesis]]''), Osman's assumption that non-ONI personnel would be familiar with a single, obscure planet among humanity's hundreds of colonies is highly doubtful.

*Captain Osman claims that the UNSC had captured and defused a Huragok "a couple of years ago", and that ONI has made several technological developments by reverse-engineering the data it contained. She implies the Engineer had died and states that ONI needs more than one Huragok so they can repair each other and reproduce.<ref>'''Halo: Glasslands''', ''page 222''</ref> Strangely, she does not mention that several Huragok were rounded up aboard the {{UNSCShip|Gettysburg}} when it returned to Earth,<ref>'''Halo: First Strike''', ''page 335'' (2003 edition)</ref> nor does she say that [[Quick to Adjust|one]] was rescued from New Mombasa and interrogated shortly thereafter.<ref>'''Halo 3: ODST''', campaign level ''[[Coastal Highway]]''</ref> It is possible that she refrained from telling the whole truth to motivate her team to board ''[[Piety]]'' and capture the Engineer aboard.

*There are a number of conflicts involving Dr. Halsey's theft of the rebel vessel ''[[Beatrice]]''. Halsey is repeatedly stated to have "hijacked" the ship (even in one of her internal monologues)<ref>'''Halo: Glasslands''', ''page 387''</ref> and it is implied that she threatened someone with her personal sidearm when she stole the vessel, an incident which CPO Mendez uses grounds for confiscating her pistol. ''Halo: First Strike'' describes the event in question, and no threats are involved when Halsey boards the vessel (which is empty and unguarded) and leaves unopposed.<ref>'''Halo: First Strike''', ''page 276''</ref> Additionally, Mendez refers to the incident as if he had been present,<ref>'''Halo: Glasslands''', ''pages 74, 386''</ref> even though he did not have first-hand knowledge that Halsey had stolen a ship; him knowing about the event would be based on Blue Team's or Halsey's accounts. Mendez was also not aware of Halsey's ulterior motives for bringing the Spartans to Onyx, as she had divulged that information only to Kurt Ambrose in private shortly before the group entered the shield world,<ref>'''Halo: Ghosts of Onyx''', ''pages 339-341''</ref> casting Mendez's paranoia about her in a questionable light. Furthermore, Mendez treats the incident as if Halsey had stolen a friendly vessel; ''Beatrice'' was in fact the personal ship of Governor [[Jacob Jiles]], an Insurrectionist leader whom hours prior had threatened to destroy [[UNSC Gettysburg|a UNSC frigate]]. Most egregiously, Admiral Parangosky lists the theft of ''Beatrice'' as one of the war crime charges brought against Dr. Halsey following the latter's arrest on [[Trevelyan]].

*According to ''Halo: Glasslands'', Dr. Halsey did not have an AI to help her decipher Forerunner symbols while in the [[Trevelyan|shield world]].<ref>'''Halo: Glasslands''', ''page 264''</ref> However, she had the "micro" AI [[Jerrod]] in her laptop in ''Halo: Ghosts of Onyx'', helping her translate Forerunner symbols while they traversed the interior of Onyx.<ref>'''Halo: Ghosts of Onyx''', ''page 353''</ref> No mention was made of Halsey losing Jerrod, and she still has her laptop after she and the other survivors had entered the shield world.<ref>'''Halo: Ghosts of Onyx''', ''page 380''</ref> 

*During an argument with Dr. Halsey, CPO Mendez claims the SPARTAN-III program lacked any form of genetic filtering.<ref>'''Halo: Glasslands''', ''pages 269-270''</ref> In ''Halo: Ghosts of Onyx'', Mendez is present at a meeting where it is established that the SPARTAN-III program did indeed have a set of genetic qualifications, a necessity because the [[Project CHRYSANTHEMUM|biochemical augmentations]] at the time were compatible only with a particular series of genetic markers and that any deviations would carry a significantly increased risk of failure. For this reason, the initial pool of candidates for [[SPARTAN-III Beta Company|Beta Company]] had to be reduced from the original projection of nearly 1,000 to 375.<ref>'''Halo: Ghosts of Onyx''', ''pages 82-83''</ref> His argument is based on the alleged lack of genetic screening making the SPARTAN-III project more morally sound than the SPARTAN-II program due to the latter's perceived elitist overtones because of its strict genetic criteria. However, this disregards that the screening was in place not only for the sake of the SPARTAN-II augmentations but also to ensure that the candidates would be fit both physically and psychologically to acclimatize to the harsh military life imposed upon them, facts of which Mendez was fully aware.

*[[Lucy-B091]] lashes out in a fit of rage and strikes Dr. Halsey in the face with strength enough to "send a shock wave right up her arm"<ref>'''Halo: Glasslands''', ''page 316-317''</ref> and leave her hand "throbbing"; based on the description of the incident, Lucy clearly exhibits no self-control in the assault. Halsey quickly recovers and does not suffer more apparent injury than a slightly bleeding nose.<ref name="gl327">'''Halo: Glasslands''', ''page 327-328''</ref> Based on prior evidence of the Spartan-IIIs' physical strength, combined with the [[SPI armor]]'s hardened gauntlet plating (as seen [[:File:HGOO Kurt Crop.jpg|here]] and [[:File:Semi-Powered Infiltration.png|here]], the knuckles and fingers are reinforced with metallic armor), such a blow would have inevitably resulted in Halsey's death. Spartan-IIIs have been stated to possess the strength of "three normal soldiers",<ref>'''Halo: Ghosts of Onyx''', ''page 99''</ref> and while Lucy is twenty at the time, Spartan-IIIs have been described as being capable of matching Sangheili and other Covenant in close quarters at only twelve years of age, effortlessly snapping the aliens' necks and limbs,<ref>'''Halo: Ghosts of Onyx''', ''page 22''</ref> demonstrating strength that would certainly be lethal against a frail, aging human. Although ''Glasslands'' offers Lucy's small size as a justification for the meager force of her punch,{{Ref/Reuse|gl327}} ''Halo: Ghosts of Onyx'' gives no indication that her physical prowess is in any way anomalous among the Spartan-IIIs as she is able to keep up with the decidedly superhuman feats of the rest of [[Team Foxtrot|her fireteam]] and the rest of Beta Company during [[Operation: TORPEDO]] and subsequent operations. Not only this but even a small Spartan-III, ''in armor'' no less, who delivered a blow with enough force to feel a shockwave to their shoulder would inflict devastating damage on their target.

*In ''Halo: Ghosts of Onyx'', the omniscient narrator states that Lucy-B091 would remain mute for the rest of her life following Operation: TORPEDO.<ref>'''Halo: Ghosts of Onyx''', ''page 27'' (''Lucy's words asking if they were alive would be her last. "Posttraumatic vocal disarticulation," the experts would eventually declare. And although recertified for duty, she would remain silent — either unable, or unwilling, to speak the rest of her life.'')</ref> However, Lucy overcomes her [[post-traumatic vocal disarticulation]] and regains the ability to speak in ''Glasslands''.

*Lucy-B091 consistently internally refers to Kurt Ambrose only as "Kurt"<ref>'''Halo: Glasslands''', ''pages 141, 144, 190''</ref> despite the fact the Spartan-IIIs knew him by his rank and surname;<ref>'''Halo: Ghosts of Onyx''', ''pages 13, 96, 117, et al.''</ref> in ''Halo: Ghosts of Onyx'', only the Spartan-IIs and Dr. Halsey refer to him as "Kurt".

*''Glasslands'' implies Naomi-010 and, presumably, the Spartan-IIs as a whole, did not know about the flash clones used to replace them.<ref>'''Halo: Glasslands''', ''pages 318-319''</ref> In ''Halo: The Flood'', a section from John-117's point of view indicates he is aware of the clone replacements,<ref>'''Halo: The Flood''', ''page 18'' (2003 edition)</ref> and both ''[[Halo: Fall of Reach]]'' and ''[[Halo: The Fall of Reach - The Animated Series]]'' depict several Spartan-II candidates seeing their flash clones as they are abducted.

*Dr. Halsey notes in an internal monologue that she had decided it was "kinder" to tell the Spartan-IIs who survived their augmentations that Serin-019 had been killed in the procedures rather than revealing that she had been cripplingly injured;<ref>'''Halo: Glasslands''', ''page 385''</ref> earlier in the book, Naomi-010 tells Serin that she believed the latter had died during the augmentation procedures.<ref name="Halo page 82">'''Halo: Glasslands''', ''page 82''</ref> In ''Halo: The Fall of Reach'', the live washouts accompany the successfully augmented Spartans to the closed-casket funeral for those who died.<ref>'''Halo: The Fall of Reach''', ''pages 60-63'' (2001)</ref> John-117 is later shown to be aware of the fate of the washouts, internally noting that the dozen crippled Spartans had been reassigned to ONI.<ref>'''Halo: The Fall of Reach''', ''page 64'' (2001)</ref> While it can be inferred that Serin was excluded from the funeral ceremony, it is suspect that Halsey would lie about her fate for the sake of kindness given that she allowed the successfully augmented Spartans to see the other washouts, many of whom were crippled far more severely than Serin.

*When the survivors in the shield world reestablish contact with the UNSC, [[Margaret Parangosky|Admiral Parangosky]] tells Dr. Halsey that it has been "five months" since John-117 and Cortana went missing after stopping the Halo Array from firing.<ref>'''Halo: Glasslands''', ''page 368''</ref> However, John and Cortana disappeared on December 11, 2552, with the UNSC receiving confirmation of this when [[Thel 'Vadam|the Arbiter]] returned to Earth on December 23.<ref>[http://halo.xbox.com/Forums/yaf_postsm286574_Glasslands-complaints.aspx#post286574 '''Halo Waypoint Forums''' - ''Glasslands complaints...'' (post by Vociferous)]</ref> The scene with Parangosky informing Halsey about their disappearance occurs in February 2553, so fewer than three months had passed at that point. Even considering the possibility that Parangosky may have lied, she would have no reason to do so, as both she and Halsey were aware of a transmission sent by Cortana on November 3 - fewer than four months earlier - in which she announced that John was on his way to Earth.<ref>'''Halo: Ghosts of Onyx''', ''pages 182-183''</ref>

*When describing the Spartan-IIIs, [[Vasily Beloi]] notes that ''"If they'd been pumped full of growth hormones and ceramics like Naomi, then it hadn't worked. They were just regular-sized kids."''<ref>'''Halo: Glasslands''', ''pages 400-401''</ref> This is inconsistent because the Spartan-IIIs' bodies are described as decidedly atypical for their age in ''Halo: Ghosts of Onyx''. Lucy-B091 is mentioned as being abnormally small for a Spartan-III with a height of 1.6 meters at the age of twelve.<ref>'''Halo: Ghosts of Onyx''', ''pages 26-27''</ref> Additionally, at twelve years old, the Spartans of Gamma Company had grown to near-adult size because of hormonal supplements,<ref>'''Halo: Ghosts of Onyx''', ''page 98''</ref> and are compared to Olympic athletes years older due to their "well-muscled" and "sculpted" physiques,<ref>'''Halo: Ghosts of Onyx''', ''page 100, 171''</ref> making it unlikely for anyone to assess them as "regular-sized kids". ''[[Halo: Last Light]]'' reiterates that most of the Spartan-IIIs are conspicuously larger than normal humans<ref>'''Halo: Last Light''', ''pages 93'' (Google Play edition)</ref> (with Lucy as a noted exception),<ref>'''Halo: Last Light''', ''page 265'' (Google Play edition)</ref> and similar to the statements in ''Ghosts of Onyx'', it is observed on several occasions that the Gamma Company Spartans' physiques are clearly not consistent with their age.<ref>'''Halo: Last Light''', ''pages 123-125'' (Google Play edition)</ref>

*''Glasslands'' maintains that Dr. Halsey attempted to hide the SPARTAN-II flash clone replacement operation from the upper echelons of ONI; Admiral Parangosky claims that she did not learn about the clones until years afterward.<ref>'''Halo: Glasslands''', ''page 431''</ref> When referenced in previous fiction the flash cloning operation is never singled out as something separate or particularly secretive in comparison to all other aspects of the program; on the contrary, ONI is unanimously identified as the chiefly responsible party as opposed to Halsey alone. In ''Halo: The Fall of Reach'', John-117's classified file, accessed by Cortana, refers to the replacement operation as an "ONI black op".<ref>'''Halo: The Fall of Reach''', ''page 270''</ref> In ''Halo: First Strike'', Halsey refers to the ''"old flash clone techniques that ONI had used to replace the originals"''.<ref name="fs129">'''Halo: First Strike''', ''page 129''</ref> In her journal, Halsey refers to the clones like any other part of the program, failing to mention any attempt to conceal it.<ref>'''Dr. Halsey's personal journal''', ''September 8, 2511''</ref> Furthermore, ''Halo: First Strike'' notes that Colonel James Ackerson had the clones monitored as they grew up and even had the bodies retrieved after they died, which calls into question Parangosky's statements of not learning about the cloning operation until years later.{{Ref/Reuse|fs129}} It is also suspect that Halsey would see it necessary to conceal this particular aspect of the program from ONI, given their oft-demonstrated neglect for moral concerns, particularly where the secrecy of their operations is concerned. Had there been an attempt to withhold information, it would have been futile from the beginning; the dozens of ONI scientists and field agents that carried out the operation would have relayed the information to ONI's leadership in the unlikely event that the ONI surveillance of the program failed to do so.
**Parangosky may have lied about Halsey's cover-up of the flash-cloning operation, setting her up as ONI's scapegoat for the morally abhorrent actions of the SPARTAN-II program. Parangosky thus could have charged Halsey with the false cover-up in addition to the genuine war crimes for which she was arrested to settle the personal vendetta between them. However, the doctor makes no attempt to dismiss the admiral's claims as false. Indeed, both characters' internal monologues indicate that the cover-up actually occurred. Halsey's failure to defend herself is noticeably contrasted with the subsequently-released [[Halo: Escalation Issue 16|16th issue]] of  ''[[Halo: Escalation]]'', in which she responds to Commander [[Sarah Palmer]]'s similar accusations thus: "''You can't be that naive. You really think I could have pulled off everything I've been accused of without the full support of ONI? Of the entire UNSC? Consider the resources. The budgets. You think those decisions were made unilaterally? Whether it was a signed form or a wink — they approved it all.''" 

*The Sangheili repeatedly refer to [[Terrence Hood|Fleet Admiral Hood]] as "Shipmaster of Shipmasters".<ref>'''Halo: Glasslands''', ''pages 258, 341, 343, 425''</ref> While not strictly a contradiction, it is somewhat out of character for the Sangheili to insist on using such an epithet. Hood's rank would draw more natural comparisons to the actual Sangheili ranks of [[Supreme Commander]] or [[Imperial Admiral]] rather than a neologism contrived from the lesser rank of Shipmaster.

===''Halo: The Thursday War''===
{{Main|Halo: The Thursday War}}

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*The {{UNSCShip|Port Stanley}} carries a large arsenal of [[nuclear weapon]]s aboard and is yet capable of remaining completely undetected over [[Sanghelios]].<ref>'''Halo: The Thursday War''', ''page 320''</ref> According to ''Halo: Ghosts of Onyx'', this would be impossible, as the [[plutonium]] in nuclear weapons negates any stealth measures upon slipspace transition by emitting an easily detectable [[Čerenkov radiation]] signature, forcing even stealth vessels to jettison any onboard nukes in order to perform a cloaked slipspace exit.<ref>'''Halo: Ghosts of Onyx''', ''page 187''</ref>
**''Port Stanley'' had been heavily upgraded with Forerunner technology, so it is possible that this flaw had been alleviated (although no such upgrade is mentioned).

*[[Catherine Halsey|Dr. Catherine Halsey]] is portrayed as being entirely unfamiliar with the concept of a fourth-generation AI and appears to believe [[Black-Box]] when he falsely claims that fourth-generation AIs are created by other AIs (after the exchange, Black-Box tells Evan Phillips that he was lying about his generation being created by other AIs).<ref name="Halo page 355">'''Halo: The Thursday War''', ''page 355''</ref> However, in ''Halo: Ghosts of Onyx'', Halsey demonstrates close familiarity with ''fifth-generation'' smart AIs and has an intimate understanding of their behavior; she is able use a [[Religion#Zen|Zen koan]] to attract the attention of the fifth-generation AI [[Endless Summer]], states that fifth-generation smart AIs like to "show off", and mentions that she wrote the subroutines that allow Endless Summer to lie.<ref>'''Halo: Ghosts of Onyx''', ''page 179''</ref>
**It is possible that Halsey feigned ignorance out of unwillingness to help Admiral Parangosky's underlings, who were responsible for her arrest and regarded her with open contempt. However, Black-Box would most likely have known the full extent of her expertise given his unrestricted access to her and ONI's files, unless Halsey managed to hide this information from ONI at large. Regardless, he appears to regard Halsey's ignorance about the development of fourth-generation AIs such as himself as genuine.

*While on [[Trevelyan]], [[Jul 'Mdama]] is said to be able to determine the passage of time based on the "position of the sun".<ref>'''Halo: The Thursday War''', ''page 346''</ref> Given the structure's nature as a full-size [[Dyson sphere|Dyson shell]], this would be impossible, as the sun would always be directly overhead at any point on the sphere's interior surface.

*A Sangheili insult for humans - ''[[nishum]]'' - is said to roughly mean "intestinal parasite".<ref>'''Halo: The Thursday War''', ''page 79''</ref> The name is derived from the Sangheili mistaking armored humans for creatures with exoskeletons, then after examining dead human bodies concluding that they are parasites inside insectoid beasts. However, the Sangheili themselves wear body armor (which is often thicker and more carapace-like in design than standard human infantry armor), as do most of the Covenant species, so it seems suspect of them to not be able tell that humans wear artificial armor just like they do.
** During a scripted conversation on the ''[[Halo 5: Guardians]]'' level "[[Before the Storm]]", a member of the [[Swords of Sanghelios]] refers to fellow Sangheili [[Sali 'Nyon]] as a ''nishum''. This may indicate that the term has been retconned into a general insult, discarding the suspect explanation provided in ''The Thursday War''.

*Dr. Halsey asks Black-Box ''"So which ship or Spartan are you assigned to?"'' upon encountering the AI.<ref>'''Halo: The Thursday War''', ''page 357''</ref> This question excludes a broad range of assignments in which AIs are commonly known to serve, while equating Spartans with ships as one of two noteworthy posts for AIs; Halsey would have no reason to presume that an AI would be assigned to a Spartan, given that Cortana's assignment to John-117 was a one-time exception and not a standard procedure among Spartans.

*[[Terrence Hood|Fleet Admiral Hood]] is suggested to be antagonistic toward Dr. Halsey; he assures Admiral Parangosky that [[Andrew Del Rio|Captain Del Rio]] is "Halsey-proof" and that the doctor will not be able to "manipulate" him.<ref>'''Halo: The Thursday War''', ''page 67''</ref> In previous fiction Hood is portrayed as one of Halsey's closest friends and allies within HIGHCOM, harshly censuring Colonel Ackerson for mocking the doctor and her Spartans and lamenting Halsey's apparent death on Reach.<ref>'''Halo: First Strike''', ''page 104'' (2003)</ref>
**It is possible that Hood became resentful of Halsey after she drew Blue Team (and consequently an entire Navy battle group) away from the defense of Earth on the premise of needing Spartans to secure Forerunner technology, when in reality she planned to hide out on Onyx.

*Professor [[Evan Phillips]] casually mentions that it is common for Forerunner [[portal]]s to displace individuals to different planets as if this information is common knowledge,<ref name="ttw181">'''Halo: The Thursday War''', ''pages 181-182''</ref> even though there is no precedent for such technology in previous fiction nor any evident reason for Phillips being informed of how Forerunner portals operate (he is a xenoanthropologist specializing in Sangheili culture).

===''Halo 4: Forward Unto Dawn''===
{{Main|Halo 4: Forward Unto Dawn}}

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*John-117 claimed that the [[Battle of Circinius IV]] resulted in the entire population, with the exception of Hestati squad, being annihilated.<ref>Halo 4: Forward Unto Dawn - John-117: "You're the only survivors."
Michael Sullivan: "In the school?"
John-117: "On the planet."</ref> However he goes on to save more survivors years later in [[Operation: PHALANX]], creating a major contradiction.

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* In ''Halo 4'', it is implied that coordinate data from an incident with the [[Composer]] from [[Installation 03]] led {{UNSCShip|Infinity}} to Requiem. No mention is made of ''Infinity'' picking up Cortana's distress call which results in the ship and its battle group making a slipspace jump toward Requiem in ''Halo 4: Forward Unto Dawn''. Although ''Infinity'' receives the distress call in ''Halo 4'', this appears to be after the ship is already near Requiem; in ''Forward Unto Dawn'', the signal is picked up while ''Infinity'' is still light-years away, as evidenced by the crew having to enter cryo-sleep for the journey.
** ''Forward Unto Dawn'' also depicts a considerably different interpretation of Cortana's introduction as depicted in the game. In the game her avatar simply winks into existence when intruders are detected aboard the ship; she then calmly (though hesitantly) revives John with the words, "Wake up, Chief. I need you." In the web series, however, Cortana experiences a series of violent personality shifts (at one point vowing to let John die with her) until the ''Dawn''<nowiki>'</nowiki>s sensors detect Requiem.<ref>Cortana:"It appears to be an alien construct. The data confirms it was not built by the Covenant. No need for more analyzing."</ref> Cortana's avatar then dramatically fades from a large sphere to a much smaller point, from which she then appears. She then wordlessly begins thawing the Master Chief's cryo chamber without using the holographic terminal seen in the game. In the level ''Dawn'' Cortana claims to be unaware of the ship's proximity to Requiem; however, she should have been able to see it through her neural link with John, so she was likely either joking or undergoing the effects of rampancy.<ref>Cortana: "Uh, I'm sorry - did I miss us orbiting a Forerunner planet at some point?"</ref>
*''Halo 4: Forward Unto Dawn'' depicts a fleet of more than two dozen cruisers and frigates accompanying ''Infinity'' to Requiem. ''[[The Commissioning]]'' shows only two {{Class|Paris|heavy frigate}}s by the time ''Infinity'' has reached Requiem, though the camera angle obscures any other ships that may be present. Regardless, this escort fleet is never mentioned in the game.
** The fleet may have been sent to deal with the [[Jul 'Mdama's Covenant faction|Covenant]] ships still in orbit above Requiem. However, the fleet is never mentioned during the level "[[Shutdown]]", when it could have been used to intercept ''[[Mantle's Approach]]'' before the Didact could escape Requiem.
** At the end of the web series, most ships in the fleet are shown entering slipspace under their own power. However, some of the vessels hold formation [[:File:FUD-Infinity-Fleet.jpg|so closely to ''Infinity'']] that they may have entered its slipspace rupture and followed its wake; the two closest frigates maintain the same formation as those seen in ''The Commissioning''. It is possible that these ships arrived alongside ''Infinity'' while the rest of the ships were outpaced due to their slower engines, thus explaining the frigates seen in the trailer. They may have been destroyed when Requiem began pulling the flagship inside, explaining the high volume of debris seen cascading toward the shield world.

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[[Linda-058]] and two other female Spartans are portrayed with long hair during the Spartans' [[SPARTAN-II augmentation procedures|augmentation procedures]]. According to ''Halo: The Fall of Reach'', all of the Spartans had their heads shaved in preparation for the procedure.<ref name="tfor78">'''Halo: The Fall of Reach''', ''pages 78-79'' (2001 edition)</ref>

===''Halo 4''===
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*John-117's size varies from cutscene to cutscene. John is five inches taller than [[Sarah Palmer]]; they are 7' 2" and 6' 9", respectively. However, in the level ''[[Infinity (Halo 4 level)|Infinity]]'' he is only minutely taller than her while in the ''[[Epilogue]]'' he towers over her by about two feet.
*The Spartan Ops cutscenes depict weapon strengths at levels exaggerated from gameplay. For instance, Thorne in ''[[Scattered]]'' is able to kill two [[Sangheili Storm]] with a [[Kelos'vaarda-pattern storm rifle|storm rifle]] with a single shot each, and [[Sarah Palmer]] in ''[[Invasion (Spartan Ops)|Invasion]]'' kills [[Promethean Knight]]s with a single shot from a [[M6H magnum|magnum]]. [[Energy shielding|Energy shields]] are also never depicted on Spartans, Elites, or Knights, with weapons damaging them as though they had no shields.
** 343 Industries writer [[Jeff Easterling]] has implied that the instance with the Prometheans is non-canonical.<ref>[https://www.halowaypoint.com/en-us/forums/db05ce78845f4120b062c50816008e5d/topics/canon-fodder-6-19-15-under-locke-keynote/a020824e-e55e-4802-b824-6d57ba6b1349/posts?page=2#post32 '''Halo Waypoint Forums''': ''Canon Fodder 6-19-15: Under Locke & Keynote (post 32 by GrimBrotherOne)'']</ref>

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*During the prologue set in the Human-Covenant war era, Spartan-IIs are depicted wearing post-war era MJOLNIR armor rather than war-era MJOLNIR armor. The Halo 4: Essential Visual Guide allegedly claims that it's an older variant that acts as a precursor to Mark VI Gen 2, however former Creative Director, [[Josh Holmes]], concurrently stated [https://twitter.com/JoshingtonState/status/474224115608731650 "We didn't have time to build S-II armor just for intro so we used the S-IV armor in its place. Canonically incorrect I know. :("] and [https://twitter.com/JoshingtonState/status/475323428430696449 "the story is canon, the specific armor representing that story is not. Does that make sense?"], creating a [[Halopedia:Canon policy|major contradiction]].
*The {{UNSCShip|Forward Unto Dawn}} had a {{Class|Charon|light frigate}} design where ''[[Halo 3]]'' left of, while ''Halo 4'' picks ups with it suddenly changing to a {{Class|Strident|heavy frigate}} design.
**This has since been clarified as merely an artistic interpretation due to behind-the-scenes developmental reasons; the ''Halo 3'' design for the ''Dawn'' is still considered the canonical design by 343 Industries.<ref>[https://www.halowaypoint.com/en-us/news/canon-fodder-have-s-moa ''Halo Waypoint'': Canon Fodder - Have S'moa]</ref>
*In John-117's accessible service record in the level "[[Dawn]]", ''Pillar of Autumn'' (a ''Halcyon''-class cruiser) is misidentified as a frigate.
*The [[Cryptum]] that preserved the [[Ur-Didact|Didact]] on Erde-Tyrene in ''[[Halo: Cryptum]]'' left him very weak, and he had to be reinvigorated through a nutrient bath to regain his strength, a process that took several days. In ''Halo 4'', the Didact's Cryptum has preserved him perfectly for over a hundred millennia and he has not suffered any kind of muscle loss.
**According to ''Halo: Silentium'', the Cryptum the Librarian imprisoned the Didact in is a "combat Cryptum", though the nature of this variant is never elaborated upon.<ref>'''Halo: Silentium''', ''page 292''</ref>
*The Didact, in both his forms, is depicted with thick, spike-like protrusions in the place of hair; he is described as having a patch of pale, bluish white fur as in ''The Forerunner Saga''.<ref>'''Halo: Cryptum''', ''page 179''</ref>
* Slipspace is described as an entirely featureless, pitch-black void in written media, a direct result of its inherently "nonvisible" nature.<ref>'''Halo: The Fall of Reach''', ''page 15'' (2001 edition)</ref><ref>'''Halo: Ghosts of Onyx''', ''page 288''</ref><ref>'''Halo: Glasslands''', ''page 85''</ref><ref>'''Halo: The Thursday War''', ''page 385''</ref> In the level [[Midnight]], though, slipspace resembles a bluish expanse with white streaks of stars being flown past. Likewise in the opening cutscene of [[S1/Departure|Departure]] slipspace appears as a kaleidoscope of colors. This may be from both ships using Forerunner slipspace engines, which have been observed [[Forerunner crystal|to create differing environments]].<ref>'''Halo: First Strike''', ''page 211-212'' (2003 edition)</ref> However, the most likely explanation is simply that this is artistic license.
*In his journal entry in the ''[[Infinity Briefing Packet]]'', [[Gabriel Thorne]] expresses uncertainty as to whether the Master Chief was the only Spartan-II. This is strange since the Spartan-IIs and their exploits were highly publicized by ONI Section Two and were widely known among both the military and the general populace throughout the final years of the Covenant War, with rumors of them having circulated for years prior.
*The [[Terminal (Halo 4)|terminals]] introduce [[Terminal (Halo 4)#Relation to ''The Forerunner Saga''|many incongruities]] with ''[[The Forerunner Saga]]''. However, 343 Industries have clarified that the terminals are a condensed version of the more complex story in the novels and should not be taken as a literal account; in-universe, this is explained with the unreliability of the [[Domain]], through which the terminal records are presented.<ref>[http://waypointassets.blob.core.windows.net/mobilecontent/legacysupport/content/assets/en-us/podcast/343Sparkast_017.mp3 '''Halo Waypoint''': ''343 Sparkast 017'']</ref>
*While Cortana was officially stated to be dead following ''[[Halo 4]]'' by both the game itself and developers,{{Ref/Game|Id=Dead1|[[Halo 4]], campaign level [[Epilogue]]|Quote=After the destruction of New Phoenix, and the death of Cortana, Master Chief must carry on.}}<ref name="Dead2">[https://www.youtube.com/watch?v=DqD2MkOwDcU Halo Xbox E3 2014 Media Briefing: Halo] ''"At the end of Halo 4, Master Chief was mourning the loss of his closest companion."''</ref><ref name="Dead3">[https://www.gameinformer.com/b/features/archive/2015/06/12/the-halo-5-guardians-cover-story.aspx The Halo 5: Guardians Cover Story] ''"I call that the ghost of Cortana, her fate is obviously very clear at the end of Halo 4. The story is really about, 'What effect did Cortana's sacrifice have on the Chief?' So it’s not about the dreamlike figure that you see."''</ref> these statements turned out to be deliberate fabrications and disinformation upon her survival in ''[[Halo 5: Guardians]]'', where developers later stated the ending of ''5'' was planned before the ending of ''4''.<ref name="Ending">[[The Sprint: Ship It]] ''"I think we knew how Halo 5 ended before we knew how Halo 4 ended. I remember discussing the end of this game real early on."''</ref>

===''Halo: Silentium''===
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*It is established that [[Path Kethona]] is the Forerunners' name for the [[Wikipedia:Large Magellanic Cloud|Large Magellanic Cloud]],<ref>'''Halo: Silentium''', ''page 35''</ref> which is correctly stated to be 160,000 light-years from the Milky Way.{{Ref/Reuse|s60}} Later, when ''[[Audacity]]'' completes its second jump toward Path Kethona, the middle distance from the [[Orion complex]] is stated to be 87 million light-years, or 60 million light-years from the galactic border.<ref name="s60">'''Halo: Silentium''', ''pages 60-61''</ref> 
**The reference to millions of light-years instead of thousands is likely a typographical error.

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*In ''Halo: Cryptum'', the Didact states that he told the Librarian what the [[Primordial]] had said to him at Charum Hakkor and that her research had changed drastically as a result.<ref>'''Halo: Cryptum''', ''page 327''</ref> In ''Halo: Silentium'', the Librarian claims that while the Didact told her about the Primordial, he did not reveal what it had said to him, and the Librarian would not find out herself until thousands of years later when she journeyed to Path Kethona.<ref>'''Halo: Silentium''', ''page 33''</ref>

*The timescales of the histories of the Forerunners and their contemporaries appear to have been extended considerably from those discussed in ''Halo: Cryptum''. In ''Silentium'', events hundreds of thousands of years past are discussed routinely, whereas in ''Cryptum'', it is mentioned that the Forerunners had little records from only fifty thousand years earlier. For example, in ''Cryptum'' it is stated that [[Ancient humanity|early humanity]] began expanding their civilization outward to the galactic margins around 150,000BC. Boundless is noted to have been studying humanity's expansion to the same regions a million years earlier.

===''Halo: Initiation''===
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The first issue of ''Halo: Initiation'' references [[Sarah Palmer]] as a lance corporal, and later corporal, during her ODST career immediately prior to her recruitment into the [[SPARTAN-IV program]]; this is corroborated by {{Plain|[https://forums.halowaypoint.com/yaf_postsm2969317_Catalog-Interaction.aspx#post2969317 a statement]}} by [[Catalog#Trivia|Catalog]]. According to Palmer's biography on the now-defunct official ''Halo 4'' website, she spent much of her Marine career as a lieutenant.<ref>[https://www.halowaypoint.com/en-us/intel/inteldetail/802c2079-395f-47a2-bab8-ca2edf879e5b/commander-palmer?category=story '''Halo Waypoint''': ''Halo 4 - Commander Palmer'']</ref> [[Andrew Del Rio|Captain Del Rio]] calls Palmer a lieutenant when ordering her to apprehend John-117 in the ''Halo 4'' level [[Reclaimer (level)|Reclaimer]], although the context of this line has since been changed with the reworking of the rank structure of [[Spartan Operations]]; Del Rio now canonically addresses an off-screen Navy lieutenant.<ref>[https://twitter.com/schlerf/status/432284571351404544 '''Twitter''': ''Chris Schlerf on Palmer's rank'']</ref> ''[[Halo 4: The Essential Visual Guide]]'' states that Palmer's leadership skill was the primary reason for her selection as a Spartan; if Palmer were a lance corporal, it is unlikely that such qualities could even be ascertained, as a lance corporal would have virtually no command experience. While it is possible that she was demoted prior to the events of ''Initiation'', this is not indicated in the comic; Jun-A266 congratulates her for her promotion to corporal, and no previous demotion is mentioned at any point. Thus, it is likely that her background as a lieutenant has simply been ignored.

===''Halo: Mortal Dictata''===
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*According to ''Halo: Mortal Dictata'', Dr. [[Graham Alban]]'s suicide occurred in [[2523]]. However, the reference to the [[Covenant]] in his suicide note dates his suicide to [[2525]] or later. This was later rectified in the [[2019]] edition of the novel correcting the year to [[2532]].

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*According to a video clip of the early days of Spartan-II indoctrination shown to [[Naomi-010]] by [[Black-Box]], Dr. Halsey lied to Naomi that [[Staffan Sentzke|her father]] had approved of her conscription and was not expecting her to return home.<ref>'''Halo: Mortal Dictata''', ''page 385''</ref> In ''Halo: The Fall of Reach'', Halsey specifically states, contrary to [[Déjà]]'s recommendations, that they will not attempt to lie to the children about their parents to motivate them out of risk that the Spartans may go rogue if they ever learned the truth.<ref>'''Halo: The Fall of Reach''', ''page 29'' (2001) (''"The truth has risks," Déjà cautioned. "So do lies," Dr. Halsey replied. "Any story fabricated to motivate the children—claiming their parents were taken and killed by pirates, or by a plague that devastated their planet—if they learned the truth later, they would turn against us."'')</ref> Halsey's notes in her [[Dr. Halsey's personal journal|her journal]] correlate with the version given in ''The Fall of Reach'', noting that ''"They deserve as much truth as we can stomach to tell them."''<ref>'''[[Dr. Halsey's personal journal]]''', ''September 23, 2517''</ref><br>ONI recordings described in ''Mortal Dictata'' also show the SPARTAN-II children exhibiting more extreme reactions to their abduction than Dr. Halsey's observations in her journal let on.<ref name="md384">'''Halo: Mortal Dictata''', ''pages 384-385''</ref> However, descriptions in ''Halo: The Fall of Reach'' are more in line with the journal's suggestion of the children being mostly calm and compliant, as it is established that their ability to cope with the intense psychological strain involved with the program was one of the criteria for their selection.<ref name="tfor46">'''Halo: The Fall of Reach''', ''pages 46-47'' (2010)</ref> The comic adaptation ''[[Halo: Fall of Reach - Boot Camp]]'' corroborates this in an added scene in which Halsey and Déjà observe that none of the children are crying during their first days in the program.<br>''Mortal Dictata'' also claims that the Spartan children were based deep underground in [[CASTLE Base]] in the first three days of the program, even though ''Halo: The Fall of Reach'' describes them being relocated to a barracks on the planet surface in the [[Reach FLEETCOM Military Complex]] immediately after their induction (though they did train at CASTLE later on in their training).<ref>'''Halo: First Strike''', ''page 181'' (2003)</ref> As stated in ''The Fall of Reach'', the first days' extreme physical training and education sessions were arranged specifically to prevent the children from having time to think about their predicament,{{Ref/Reuse|tfor46}} yet the nature of the sessions described in ''Mortal Dictata'' allows the latter scenario to occur. The three days in CASTLE base could also not have occurred prior to Halsey's introduction to the program, as the children had only recently been awakened from cryo-sleep at the time and were only informed of their new purpose during Halsey's induction session. The military-oriented focus, intense pace and ruthlessness of the initial training are also nowhere to be seen in ''Mortal Dictata''<nowiki>'</nowiki>s descriptions, which suggest a comparatively leisurely acclimation period.{{Ref/Reuse|md384}}
**In light of these contradictions, it is not out of the question that ONI tampered with the records or simply forged footage to make Halsey's part in the program look more morally reprehensible as part of their campaign to smear her reputation; or, more specifically, to manipulate Naomi in particular. Indeed, while the aforementioned footage is said to be from official recordings Naomi is watching on a data pad, it is ambiguous how much of the sequence described in the book is factual as Black-Box is directly interfacing with Naomi's mind through her neural implant to trigger her childhood memories and repeatedly points out the fallibility of human memory prior to the session.<ref>'''Halo: Mortal Dictata''', ''page 375-376''</ref>

*The SPARTAN-II candidate abduction process is depicted with several incongruities. [[Retrieval team Theta 2]] is shown to first kidnap Naomi and transfer her clothes to the flash clone, which is only then released (several kilometers from the spot where she was originally taken) but not before Naomi temporarily escapes, causing the operation to last several hours.<ref>'''Halo: Mortal Dictata''', ''page 380''</ref> This drives her family to panic about her disappearance and an extensive search operation is organized before her clone is found. The need to transfer the real Naomi's clothing to the clone is questionable, given that ''[[Halo: Fall of Reach]]'', ''[[Halo: The Fall of Reach - The Animated Series]]'' and ''[[Scanned]]'' depict the clones wearing duplicate clothing, enabling ONI to switch the children on site and thus removing the need for a potentially suspicious disappearance before the clone is returned.<ref>'''[[Scanned]]'''</ref><ref>'''[[Halo: Fall of Reach - Boot Camp]]'''</ref>

*Staffan Sentzke matter-of-factly references the Flood's arrival on Earth during the [[Battle of Voi]], yet Staff Sergeant Geffen gives no indication that a civilian should not be aware of this occurrence.<ref>'''Halo: Mortal Dictata''', ''page 192''</ref> ''Halo: Spartan Assault'' states that glassing of the [[Tsavo]] region (in reality meant to cauterize the infestation) was officially declared a Covenant sneak attack to prevent knowledge of the Flood from leaking to the public.<ref>''Halo: Spartan Assault'', ''Flood Mission'' introductory cutscene</ref>

*Black-Box references Dr. Halsey's termination of [[Araqiel]] as a cold-blooded murder; he makes a similar suggestion in ''The Thursday War''.{{Ref/Reuse|Halo page 355}}<ref name="md363">'''Halo: Mortal Dictata''', ''page 363''</ref> In spite of his personal dislike of Halsey, Black-Box (a high-level ONI AI) should be able to acknowledge that purging AI constructs was a relatively common practice throughout the war as part of the [[Cole Protocol]],<ref>'''Halo: First Strike''', ''page 208'' (2003)</ref> yet he regards the incident as a unique act of cruelty without precedent.{{Ref/Reuse|md363}} It is strange that BB is aware of the incident in the first place, as [[CASTLE Base]] had been evacuated of personnel at the time<ref>'''Halo: First Strike''', ''page 121'' (2003 edition)</ref> and any means of off-planet communication had been cut by the Covenant long before. BB also blatantly disregards the context of the incident as detailed in ''[[Halo: First Strike]]'': not only was Halsey acting in self-defense, with Araqiel threatening to kill her,<ref>'''Halo: First Strike''', ''pages 127-128'' (2003 edition)</ref> but her actions were also in accordance with ONI's [[Operation: WHITE GLOVE]], which entailed the destruction of any remaining AI in the facility to prevent their capture by the Covenant (although Halsey had not yet formally implemented the protocol at the time). WHITE GLOVE also forced Halsey to destroy [[Kalmiya]], one of her personal AIs,<ref>'''Halo: First Strike''', ''page 135'' (2003 edition)</ref> something Black-Box never mentions when referencing the incident.

*[[Plasma torpedo]]es aboard ''[[Pious Inquisitor]]'' are referenced as physical munitions stored in a dedicated "torpedo bay".<ref>'''Halo: Mortal Dictata''', ''pages 439, 443, 445, 446''</ref> In previous fiction, plasma torpedoes have been established as shaped agglomerations of electromagnetically-guided plasma, not unlike the bolts fired by handheld plasma weapons. The "torpedoes" are brought into existence at the time the weapon fires and do not exist in any meaningful capacity aboard the vessel.<ref>'''Halo: First Strike''', ''page 171''</ref>
**The references to "plasma torpedoes" can be interpreted as referring to the ship's supply of superheated plasma used to generate the torpedoes, although the wording used suggests that the torpedoes themselves are stored aboard the ship.

===''Halo: Escalation''===
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*In [[Halo: Escalation Issue 15|Issue #15]], the Zealot conversing with Jul' Mdama at the start changes armor styles and colors between panels. Initially he wears white armor in the likeness of ''Halo: Reach''<nowiki>'</nowiki>s Zealots, then on the following page he has red armor in the likeness of ''Halo 4''<nowiki>'</nowiki>s Zealots.
*The Janus Key's red and blue halves frequently swap colors in between issues.
*In [[Halo: Escalation Issue 20|Issue #20]], Dr. Glassman faints from the smoke and Palmer has Tanaka carry him. Subsequent art depicts him standing and running in multiple panels before Tanaka informs the others that he is "waking up".

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*As in ''[[Spartan Ops]]'', [[Energy shielding|energy shields]] are never depicted on Spartans or Elites, leading to instances like Thorne being severely wounded from a single Needler shot in ''[[Halo: Escalation Issue 22|Issue #22]]''.
*[[Halo: Escalation Issue 9|Issue #9]] reveals the Ur-Didact's plan to use a Halo against Earth, killing all life on the planet shortly after his [[New Phoenix Incident|attack on New Phoenix]]. However, the Didact's opposition to using the Halos is presented as one of his core values in earlier fiction, serving as the impetus for his first exile in ''Halo: Cryptum''. ''Halo: Silentium'' shows that he continued to abhor the thought of activating the Array even after his mental torment by the [[Gravemind]] drove him to enact his crusade against humanity.<ref>''Halo: Silentium'', String 26: "The Halos? Violating the Mantle all over again, with even greater destruction! Wiping out all intelligent life across this galaxy!... If we fire Halo, we lose everything."</ref>
**The Didact's willingness to use a Halo likely stems from his second, 100,000-year exile on Requiem, during which he was isolated from the [[Domain]] and most other external stimuli. This solitude led him to dwell on his hatred of humanity for millennia,<ref>'''Spartan Ops''': ''[[Key]]''</ref><ref>'''Halo: Silentium''', ''String 37''</ref> culminating in his willingness to forsake one of his most sacred principles and commit genocide. The Didact may regard his actions in a similar manner to the [[Conservation Measure]]: though the majority of humans would perish, the millions composed in New Phoenix would live on in digital form.
*In Issue #10, the Ur-Didact is defeated by launching Installation 03's control room, with him in it, into the [[Composer's Forge]], resulting in the Composers stored there activating and composing him.<ref>[https://www.halowaypoint.com/en-us/universe/characters/didact '''Halo Waypoint''': ''Didact'']</ref> In ''Halo 4'' Terminal 6, the Didact claims that his most recent mutation renders him immune to the Composer, hence why he was the only Promethean who did not become mechanical like the rest. This is supported by the final level of ''Halo 4'', [[Midnight]], where the Didact is seen floating inside his Composer's actively firing beam without any ill effects.
**As the Composer's Forge held multiple Composers, it may have been that several composition beams rather than just one were enough to override his immunity. However, this raises the question of why he could not have used multiple Composers on himself at the time of the Forerunner-Flood war, given his seemingly free access to the Composer's Forge.
**The discrepancy is joked about in ''[[Halo 5: Guardians]]'', where the Unggoy [[Dimkee Hotay]] may remark: “I knew the Didact. He said like three words. Three! He said ‘I can’t be Composed’.”<ref>'''Halo 5: Guardians'', ''campaign level [[Alliance]]''</ref>
*In Issue #22, Catherine Halsey answers a hypothetical scenario in which she is asked whether she would enslave a sentient species for a chance at a Flood vaccine or cooperate with them for a slightly smaller chance, by saying she would take the former route of sacrificing many for the few. In ''Halo: First Strike'', Halsey tells John she has tired of sacrificing many for the few, feeling guilt over her past actions and saying she should have tried to save everyone rather than settling for the majority.<ref>'''Halo: First Strike''', ''page 296'' (2010 edition)</ref> This informs her abduction of Kelly-087 later in the novel, as well as her attempt to sequester Blue Team and the Spartan-IIIs inside [[Shield World 006]] in ''Halo: Ghosts of Onyx''.

===''Halo: Broken Circle''===
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*In Chapter 14, the narrator mistakenly refers to [[Trok 'Tanghil]] as [[Ernicka the Scar-Maker]].<ref>'''Halo: Broken Circle''', ''page 200''</ref>

*The [[Jiralhanae]] homeworld is erroneously called [[Oth Sonin]] in one reference.<ref>'''Halo: Broken Circle''', ''page 221''</ref> The novel previously identifies the planet correctly as [[Doisac]];<ref>'''Halo: Broken Circle''', ''page 211''</ref> Oth Sonin is the name of Doisac's star system.

*It is stated that [[Bal'Tol 'Xellus]]' "heart sank at the sight".<ref>'''Halo: Broken Circle''', ''page 310''</ref> This idiom is out of place as the Sangheili have two hearts, something that is acknowledged several times in the novel.

*[[The Refuge]] is described inconsistently; in the first description, the eco level's "ceiling" is said to be convex<ref>'''Halo: Broken Circle''', ''page 35''</ref> and then concave in all subsequent descriptions.<ref>'''Halo: Broken Circle''', ''pages 51, 75, 139''</ref>

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*Throughout the novel, the Ages of the [[History of the Covenant|Covenant's history]] are referenced as if each of the nine named ages were a singular and unique span of time. In previous fiction the Covenant age system has been established as being non-sequential, with each age gaining one of nine existing names according to major events that occurred in that age. For example, the [[Ages of Reclamation|Ninth Age of Reclamation]] (the period of the Human-Covenant War) is referred to simply as the "Age of Reclamation". There is implied to have been only a single "Age of Conversion" during which species were incorporated into the Covenant instead of [[Ages of Conversion|multiple numbered ages]] with that name.<ref>'''Halo: Broken Circle''', ''page 209-210''</ref>

*One description suggests [[High Charity]] still maintains a translucent atmospheric shield in lieu of its solid dome as of [[2552]], giving individuals in the city a view of the space outside much like at the time the station was still under construction.<ref>'''Halo: Broken Circle''', ''page 236''</ref> All depictions of the city-station in the modern era show the dome as being entirely opaque with no view outside.

===''Halo: Nightfall''===
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*[[Michael Horrigan]] remarks that [[Alpha Shard]] has a surface area of 96&nbsp;km<sup>2</sup>. Based on Installation 04's established surface width of 318 kilometers and the fragment's length and curvature, the shard's surface area would be hundreds of thousands of square kilometers.

*[[Jameson Locke]] implies that the [[HAVOK tactical nuclear weapon]] has a blast radius of 100 kilometers. The screen on the device later specifies that the weapon causes complete destruction within seven kilometers, and light damage for 44 kilometers. Despite this, the fireball from the same warhead completely overwhelms Alpha Shard's width of 318 kilometers.

*The identification patch on Randall Aiken's uniform shows his blood type to be O+, though his service file seen on [[Jameson Locke]] data pad lists Aiken's blood type as AB-. This is likely a production oversight.

===''Halo: New Blood''===
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*Narrator [[Edward Buck]] states that Mickey "sounded as grim as a medic telling a soldier that the only good thing about him bleeding out on the battlefield was that his cancer wouldn't get him first."<ref>''[[Halo: New Blood]]'', Chapter 1''</ref> In ''[[Midnight in the Heart of Midlothian]]'', cancer is described as a disease rarely seen since the 22nd century, and that it had become so uncommon that [[Michael Baird]] had never even heard of it until he was diagnosed.<ref>'''[[Halo: Evolutions]]''', ''[[Midnight in the Heart of Midlothian]]'', page 81</ref> Cancer is also described as "easy to treat" with 26th century medicine. It is therefore unlikely that Buck would use cancer as a trivial example of a deadly disease.

===''Halo: Hunters in the Dark''===
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*It is stated that systems on [[Installation 07]] control the "shifting of tectonic plates."<ref>'''Halo: Hunters in the Dark''', ''page 23'' (Google Play edition)</ref> As seen in ''Halo 3'' and ''Halo: Primordium'', the Halos have no tectonic plates as the ground is only several dozen meters thick, with solid foundational material underneath sculpted to create natural-looking terrain.

*The [[elevator]] leading to the central chamber of the [[Installation 00 Citadel|Ark's Citadel]] is said to descend from the antechamber into the structure's main room.<ref>'''Halo: Hunters in the Dark''', ''pages 170-171'' (Google Play edition)</ref> In ''[[Halo 3]]'', the same elevator ascends into the main room.

===''Hunt the Truth''===
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*[[Benjamin Giraud]] discovers an array capable of [[superluminal communications]] in a pre-[[Human-Covenant War]] ONI facility on [[Bliss]],<ref>'''[[Hunt the Truth]]''', [[Hunt the Truth Season 1|Season 1]], ''Episode 11: DOWN TO THE BONE''</ref> when according to ''[[Halo: Contact Harvest]]'' messages carried aboard starships were humanity's only means of FTL communication as of 2525<ref>'''Halo: Contact Harvest''', ''page 35''</ref> and in ''[[Halo: Ghosts of Onyx]]'', the [[slipspace COM launcher]] was still the only way of delivering messages without a courier ship as of early [[2551]].<ref>'''Halo: Ghosts of Onyx''', ''page 105''</ref> While the array is eventually revealed to be a post-war creation created by ONI to trap Ben,<ref>'''[[Hunt the Truth]]''', [[Hunt the Truth Season 1|Season 1]], ''Episode 13: IN THE BAG''</ref> he does not find its surprisingly advanced technology to be out of the ordinary.

===''Halo: Last Light''===
{{Main|Halo: Last Light}}

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*[[Frederic-104]] estimates that [[Veta Lopis]] is "about half" his height without armor.<ref>'''Halo: Last Light''', ''page 28'' (Google Play edition)</ref> This is unlikely, as this would make her only around 108 centimeters tall.

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*[[Olivia-G291]] is consistently called by the nickname "'Livi". It is stated in both ''Ghosts of Onyx'' and ''Glasslands'' that she is nicknamed "O" because of her skill in stealth; she is considered "as whisper quiet as her vowel namesake."<ref>'''Halo: Ghosts of Onyx''', ''page 116''</ref><ref>'''Halo: Glasslands''', ''page 37''</ref>
*When describing the history of her creation, [[Intrepid Eye]] claims that the [[Maginot Line|Jat-Krula]] defensive sphere was constructed by the [[Builder]]s after the [[Flood]]'s re-emergence and the [[Warrior-Servant]]s' first delaying actions to contain the parasite.<ref>'''Halo: Last Light''', ''page 264'' (Google Play edition)</ref> According to ''[[Halo: Silentium]]'', the Jat-Krula was already in existence over half a million years before the [[Ur-Didact]] was born.<ref>'''Halo: Silentium''', ''pages 104-105''</ref>
*In an attempt to silence Veta Lopis, Intrepid Eye seizes control of Fred-104's Mjolnir armor and attempts to kill her.<ref>'''Halo: Last Light''', ''chapter 27''</ref> However, in ''[[Halo: The Fall of Reach]]'', Dr. Halsey assures John-117 that an AI (in this case Cortana) cannot control Mjolnir, explaining that while Cortana could increase his reaction time by translating the impulses in his motor cortex directly into motion, she couldn't make him send those impulses.{{Ref/Reuse|Halo page 252}}
**As a more advanced Forerunner AI, Intrepid Eye may not be subject to the same restrictions that human AIs have. Intrepid's measure of control also seems to be restrained to the armor itself, as Fred's mind remains his own and fights against her, suggesting she is projecting her own version of neural impulses into Mjolnir rather than making Fred send them. This is supported by Intrepid's previous lack of control when the armor is empty, as the AI finds she cannot move the armor when there is no neural interface plugged into it.<ref>'''Halo: Last Light''', ''page 296''</ref>
*During the attempt to escape the [[Montero Cave System]], it is claimed that [[Olivia-G291]] was just as blind as [[Veta Lopis]] without the aid of her [[SPI]] helmet.<ref>'''Halo: Last Light''', ''page 175''</ref> However, this is contradictory to the [[Project CHRYSANTHEMUM|augmentation]] that all Spartan-IIIs were given, which not only boosts vision during the dark but overall vision as well.<ref>'''Halo: Ghosts of Onyx''', ''page 102''</ref>
**As the section is from Lopis' point of view and ostensibly describes her thought process, it is possible to regard this as an example of unreliable narration, with Lopis being unaware of the Spartans' augmented vision. However, nothing in the narrative is shown to contradict her assumption.

===''Halo: The Fall of Reach - The Animated Series''===
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*At least three Spartan-II candidates are depicted dying early in the training. Halsey's narration refers to this (in an uncharacteristically dismissive manner) as "removing the chaff from the wheat". All previous canon sources explicitly state that all seventy-five trainees survived until the augmentations. Nevertheless, following the [[SPARTAN-II augmentation procedures]] Halsey explicitly states that 27 children died, representing 36 percent of the candidates, math which holds true only if all 75 underwent the procedures.

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Like ''[[Halo: Fall of Reach]]'', the ''Animated Series'' departs from the source novel in numerous instances, with many liberties taken to better suit the medium. As it is not a particularly strict adaptation of the novel, one may regard it as an alternate interpretation of the original story, as opposed to an unintentionally contradictory narrative or a retcon. For a list of differences between the novel and the animated adaptation, see [[List of changes in Halo: The Fall of Reach rereleases|here]].

===''Halo 5: Guardians''===
{{Main|Halo 5: Guardians}}
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*In the trailers ''[[A Hero Falls]]'' and ''[[The Hunt Begins]]'' (which are shown to be canonical by their inclusion in ''[[Hunt the Truth]]''<ref>[http://huntthetruth.tumblr.com/image/130137892268 '''Tumblr''': ''Hunt the Truth'' (image)]</ref>), John and Blue Team are depicted as on the ground when the [[Guardian]] of [[Meridian]] emerged, running to reach it while avoiding a collapsing city's debris.<ref>[https://www.youtube.com/watch?v=jBCAtGvTi-Y '''YouTube''': ''Halo 5 Trailer: A Hero Falls LIVE ACTION TRAILER'']</ref> In the game, Blue Team was already aboard the Guardian before it awakened.<ref>'''Halo 5: Guardians''', ''campaign level [[Evacuation]]''</ref>
**This could relate to the fact that there were earthquakes while Osiris was inside the mines, giving a sense the Guardian was waking during that instead. As the main body of the Guardian was not shown in the trailers, it can be assumed the main body did not rise till after Blue Team entered. The fact Blue Team entered a portal at [[Apogee Station]] supports the journey they took.
**Most of the marketing was misleading in general as [[All Hail]] and [[The Cost]] ads have no relevance to the story.
*While Cortana was officially stated to be dead following ''[[Halo 4]]'' by both the game itself and developers,{{Ref/Reuse|Id=Dead1}}{{Ref/Reuse|Id=Dead2}}{{Ref/Reuse|Id=Dead3}} these statements turned out to be deliberate fabrications and disinformation upon her survival in ''[[Halo 5: Guardians]]'', where developers later stated the ending of ''5'' was planned before the ending of ''4''.{{Ref/Reuse|Id=Ending}}

===''Halo: Shadow of Intent''===
{{Main|Halo: Shadow of Intent}}

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*[[San'Shyuum]] are said to lack earlobes, with their ear-analogs being just holes on the sides of their heads.<ref>'''Halo: Shadow of Intent''', ''page 6'' (Google Play edition)</ref> However, in the remastered cutscenes of ''[[Halo 2: Anniversary]]'', the wattles of San'Shyuum are depicted as long earlobes.<ref>[[:File:H2A-POT.jpg|Image of the Prophet of Truth in ''Halo 2: Anniversary'']]</ref>
*The prototype Halo that is tested on Sangheili prisoners annihilates them entirely, leaving no bodies or even trace particles.<ref>'''Halo: Shadow of Intent''', ''page 8'' (Google Play edition)</ref> According to ''[[The Forerunner Saga]]'', the Halo effect merely destroys an organism's nervous system but leaves the bodies intact, requiring the use of [[solute]] in the atmosphere to disintegrate the dead bodies thereafter.<ref>'''Halo: Silentium''', ''page 19''</ref><ref>'''Halo: Cryptum''', ''page 132''</ref>
**It is possible that, being a prototype Halo, that specific weapon was designed to annihilate without use of a solute.
*[[Prelate]] [[Tem'Bhetek]] wields an arm shield made of [[hard light]].<ref>'''Halo: Shadow of Intent''', ''pages 51, 53, 55'' (Google Play edition)</ref> According to the [[Minister of Discovery]], the Covenant had never learned to reverse-engineer hard light technology by the time of High Charity's fall to the Flood.<ref>'''Halo: Evolutions, Volume II''', ''"Wages of Sin", page 291''</ref>

===''Halo: Fractures: Extraordinary Tales from the Halo Canon''===
{{Main|Halo: Fractures}}

====''Lessons Learned''====
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*[[Jun-A266]] is referred to as having been a member of [[SPARTAN-III Beta Company|Beta Company]] alongside Tom and Lucy before being pulled out for another operation.<ref>'''Halo: Fractures''', ''"[[Lessons Learned]]"'', ''page 4''</ref> However, all prior sources depict Jun as being a member of [[SPARTAN-III Alpha Company|Alpha Company]].<ref name="universe">[https://www.halowaypoint.com/en-us/universe/characters/jun-a266 '''Halo Waypoint''': ''Jun-A266'']</ref><ref>'''[[Halo: The Essential Visual Guide]]''', ''page 104''</ref><ref>'''[[Halo Encyclopedia (2009 edition)]]''', ''page 115'' (2011)</ref><ref>[http://halo.bungie.net/projects/reach/article.aspx?ucc=personnel&cid=24522 '''Bungie.net''': ''Jun-A266 Personnel Profile'']</ref> Strangely, ''Lessons Learned'' actually mentions Jun's full Spartan tag, in which the "A" indicates Alpha Company, in the sentence immediately before he is mistakenly identified as being from Beta Company.
*The narration mentions Tom and Lucy ''"joining Blue Team to recover an ancient AI on the hostile colony of Gao."''<ref>'''Halo: Fractures''', ''"Lessons Learned"'', ''page 12'' (Google Play edition)</ref> Though this is not technically inaccurate, the wording is peculiar, as it implies the pair joined Blue Team specifically for [[Operation: JOVIAN WHISTLE]]. In fact, Tom and Lucy had already been part of Blue Team for a few months at that point.
*It is stated that Tom and Lucy had ''"gone through countless hours in zero-G, both in training and in combat, but they'd usually been wearing Mjolnir armor while doing so."''<ref>'''Halo: Fractures''', ''"Lessons Learned"'', ''page 5'' (Google Play edition)</ref> It is improbable that Tom would regard the use of Mjolnir armor a "usual" occurrence in training or combat situations, as he would have been far more used to using [[SPI armor]] for most of his career. While it is likely that he and Lucy were trained to wear Mjolnir armor following their assignment to the Spartan branch, the story implies that they had been serving solely as instructors following the events of ''[[Halo: Last Light]]'', and does not otherwise mention them participating in combat after the mission on Gao, during which they still wore SPI armor.

====''Breaking Strain''====
{{Main|Breaking Strain}}

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*Captain [[Darren Leone]] knows that [[Kevin-A282]] is a member of SPARTAN-III Alpha Company. By virtue of Kevin's service with Alpha Company, Leone is shown to be aware that Kevin "... had seen some of the worst of the war with the Covenant, on colonies like Kholo and Meridian, even Sigma Octanus IV not long ago."<ref name="HFBS">'''Halo: Fractures''', ''''Breaking Strain'''' ''pages 65-66''</ref> Given the top-secret nature of the SPARTAN-III program (which was never declassified during the war) it is exceedingly unlikely that Leone (who prior to the events of the story was merely the helmsman on a [[UNSC Dark Was the Night|cargo tender]]) would be aware of the Spartan-IIIs as a distinct formation from the publicly avowed Spartan-IIs at all, let alone that he would be aware of their internal organization and operational history. Furthermore, Leone's reflection on Kevin's past service implies the whole of Alpha Company (rather than just Kevin and his team) had fought in the aforementioned battles. In fact, the vast majority of Alpha Company had been killed during [[Operation: PROMETHEUS]] in [[2537]], two years before the [[Battle of Kholo]] and well over a decade before the conflicts at [[Battle of Meridian|Meridian]] and Sigma Octanus IV. Kevin is a "cat 2" deployed outside his original company; though several "cat 2s" from Alpha Company remained active after Operation: PROMETHEUS, referencing the company as if it had, as a whole, survived as late as the [[Battle of Sigma Octanus IV]] in July 2552 is highly erroneous. Leone's point-of-view narration also notes Alpha Company as "one of the longest-serving SPARTAN-III units."{{Ref/Reuse|HFBS}} Only two comparable units, Beta and [[SPARTAN-III Gamma Company|Gamma Companies]], were ever founded, so such a comparison holds little weight.

====''Promises to Keep''====
{{Main|Promises to Keep}}

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*The [[Engineer (rate)|Engineers]] are established as a [[rate]] composed of members of the Forerunner species.<ref name="frac83">'''Halo: Fractures''', "[[Promises to Keep]]", ''page 83'' (Google Play edition)</ref> Previously mentioned only once, in ''[[Halo: Cryptum]]'', context in that novel indicated that the "Engineers" actually referred to the [[Huragok]], not a class of Forerunners;<ref>'''Halo: Cryptum''', ''page 298'' (''"Thus were all the rates represented, except for the Engineers, of course."'')</ref> the author, [[Greg Bear]], later confirmed this in a forum post.<ref>[http://www.gregbear.com/archives/board_2014_1.htm '''Greg Bear''': ''Discussion Board Archives January - June 2014''] (''"In this usage, and in Halo, "engineers" refers to a special group of beings not immediately related to the Forerunners. Look it up!"'')</ref>
*It is stated that the Forerunners did not return to [[Maethrillian|the Capital]] between the [[Fate of Maethrillian]] and their expedition to restore the [[Domain]] over a century after the Halos had been fired.{{Ref/Reuse|frac83}} However, ''[[Halo: Silentium]]'' states that the Forerunners rescued survivors from deep within the Capital after Mendicant Bias' attack,<ref>'''Halo: Silentium''', ''page 18''</ref> and that the Capital system was overwhelmed by the Flood only later in the war, at which point the Council was moved to the [[greater Ark]].<ref>'''Halo: Silentium''', Strings 25 and 28</ref>

====''Rossbach's World''====
{{Main|Rossbach's World (story)}}

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*In the short story, ''Rossbach's world'', [[Serin Osman]] remembers that her [[Teddy|abductor]] was a male ONI agent.<ref>'''[[Halo: Fractures]]'', ''Page 344''</ref> However, in ''Halo: Mortal Dictata'', it is stated that the agent was a woman.

===''Halo Wars 2''===
{{Main|Halo Wars 2}}

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*Various assets designed by [[Creative Assembly]] (seen on in-game models, unit cameo icons, menu and [[Blitz]] card art, and the main menu model diorama) differ from their counterparts in [[Blur Studios]]' pre-rendered cutscenes. For example, Creative Assembly's Marines (gameplay) wear armor that resembles the [[UNSC Marine Corps Battle Dress Uniform#Post-war BDU|post-war version]] introduced in ''Halo 4'' and wield [[MA37 assault rifle]]s which is canonically standard-issue for the Army rather than the Marine Corps' MA5; whereas Blur's Marines (pre-rendered cutscenes) wear the [[UNSC Marine Corps Battle Dress Uniform#Insurrection era model|armor model]] from Blur's cutscenes in the original ''Halo Wars'', and they use Marine-issue weapons such as the [[BR55 battle rifle]]. Creative Assembly's interpretation of Spartan Red Team's armor resembles a hybrid of the Mark IV, Mark V, and Mark VI; in cutscenes, mission briefings, and in-game communications, they wear their armor from the previous game. Notably, [[Douglas-042]] is consistently represented during communications by a headshot of his original helmet throughout the game, even though it is destroyed near the beginning of the campaign.
**The disparity in the Marines' armor may be due [[Isabel]] modernizing the {{UNSCShip|Spirit of Fire}}<nowiki>'</nowiki>s production facilities and design templates.{{citation needed}} It is possible that some Marines assigned to the ship (those seen in cutscenes) continued to wear the older model. The real world reason is likely due to the two separate teams (Blur and Creative Assembly) starting their versions of Marines at different times. 
**The Spartans of Red Team canonically upgraded their suits using modifications by [[Serina]] and Isabel as well as by incorporating [[MJOLNIR Powered Assault Armor (GEN2)|Mjolnir GEN2]] components sourced from the Ark.<ref name="Art">[https://www.halowaypoint.com/en-us/news/the-art-of-war-s '''Halo Waypoint''' - ''Canon Fodder: The Art of War(s)'']</ref> [[343 Industries]] writer [[Jeff Easterling]] has stated that the disconnect between Creative Assembly's and Blur's Mjolnir designs is due to resource constraints.<ref>[https://web.archive.org/web/20180525021453/http://www.haloarchive.com/forum/topic/9-canon-fodder-and-random-lore-chat/?page=252&tab=comments '''Halo Archive''', ''GrimBrother One's comment on Red Team's Mark IV designs'']</ref>
*[[Alice-130]] is shown issuing orders to Marines in the menu art for the level "[[Hold the Line]]", even though the mission is actually led by Douglas-042.
*According to its [[Phoenix Log]] entry, the [[EV-44 Nightingale]] was developed very recently as of 2559, and it is due to the craft's relatively simple structure that its design template could be adapted to ''Spirit of Fire''<nowiki>'</nowiki>s older factory lines. In the campaign mission "[[The Signal]]", however, Douglas-042 (who has been in cryo-sleep since 2531) recognizes the craft and is aware of its medical response role before contact with the Ark's UNSC presence is made. Furthermore, DLC for the game later revealed that ''Spirit of Fire''<nowiki>'</nowiki>s shipboard AI, [[Serina]], designed a theoretical variant of the Nightingale, the [[ZAV-48 Frostraven]], at some point before her final dispensation in [[2537]].<ref>[https://www.halowaypoint.com/en-us/news/stay-frosty '''Halo Waypoint''' - ''Canon Fodder: Stay Frosty'']</ref>

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*Jerome-092 is shown carrying Isabel aboard his [[Mark IV]] armor at various points in the campaign. While supported by Jerome's armor, Isabel is shown to be aware of her surroundings and able to function normally.<ref>''Halo Wars 2'', cutscenes "Atriox", "Action/Reaction"</ref><ref name="The Signal">''Halo Wars 2'', campaign level "[[The Signal]]"</ref><ref>''Halo Wars 2'', campaign level "[[Under the Dark]]"</ref> However, the ability for Mjolnir armor to support an AI was not introduced until the second generation of the [[Mark V]] (the first model to feature the necessary memory-processing superconductor layer) entered service in [[2552#August|August 2552]].
**Although the Spartans' suits were canonically upgraded,{{Ref/Reuse|Art}} which may explain Jerome's suit's ability to support Isabel later in the game, she is nonetheless shown to function normally during the escape from the Henry Lamb Research Outpost, which occurs before Jerome's armor could have been outfitted with the necessary superconducting layer.{{Ref/Reuse|The Signal}}

===''Halo: Meridian Divide''===
{{Main|Halo: Meridian Divide}}

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*Captain Delletorre says that "''all Spartan-IIIs have their genetic code modified as part of their treatment.''"<ref>'''Halo: Meridian Divide''', ''Chapter 21''</ref> Although Spartans are frequently referred to as genetically-augmented in external media, this is actually a common misconception. All previous canon consistently states that Spartan-II and Spartan-III candidates were only subjected to genetic ''screening'' to determine their suitability before being subjected to biochemical and biomechanical augmentations in [[Project ASTER]] and [[Project CHRYSANTHEMUM]], respectively. It was not until the [[SPARTAN-IV program]] and [[Project ORCHID]] that Spartans were subjected to gene therapy.

===''Halo: Shadows of Reach''===
{{Main|Halo: Shadows of Reach}}

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*John-117 describes himself as "forty-seven years old" via internal dialogue.{{Ref/Novel|Id=SoR8|HSoR|Chapter=8}} However, with his birth date well established as [[2511#March|March 7, 2511]],{{Ref/Book|Id=H4EVGMasterChief|H4EVG|Section=Characters, Campaign|Page=10 (Master Chief)}}{{Ref/Site|Id=HWUCMasterChief|URL=https://www.halowaypoint.com/en-us/universe/characters/master-chief-john-117|Site=Halo Waypoint|Section=Universe, Characters|Page=Master Chief|D=12|M=11|Y=2020|LocalArchive=https://archives.halopedia.org/waypoint/www.halowaypoint.com/en-us/universe/characters/master-chief-john-117.html}} John would be 48 years old during the events of the novel, which takes place in [[2559#October|October 2559]].{{Ref/Site|Id=CFshadows|D=01|M=6|Y=2020|URL=https://www.halowaypoint.com/en-us/news/shadows-of-the-former|Site=Halo Waypoint|Page=Canon Fodder - Shadows of the Former}}
*While ''[[Halo: Rise of Atriox]]'' established that [[Atriox]] never hated [[humans]],<ref name=AngryAtriox>[https://www.previewsworld.com/Article/195788-Angry-Atriox-Brings-Hell-To-Halo Angry Atriox Brings Hell To Halo] ''"He would tell the soldiers that they, too, are nothing but expendable. They are nothing more than cannon fodder to be thrown at their enemies. He would tell them that he doesn’t blame them for what they are. He bears them no malice. But he would also tell them that he offers no mercy. They have a role to play, just as he does, and that means that he must kill them all."''</ref>{{Ref/Comic|Id=ForWhat|[[Halo: Rise of Atriox Issue 2|Rise of Atriox Issue 2]]|Quote=My brothers fall in the war against your kind. And for what?}} ''Shadows of Reach'' portrayed Atriox hating humans (including those allied to him) creating a major contradiction of his character.{{Ref/Novel|Halo: Shadows of Reach|Chapter=21}} This was later corrected in ''[[Halo: Divine Wind]]'' where Atriox was stated to value all [[Banished]] humans and was upset with [[Pavium|Pavium's]] decision to kill some.{{Ref/Novel|Halo: Divine Wind|Chapter=6|Page=102|Quote=Atriox and his retinue had been rather unhappy with that decision, considering humans as valuable assets to the Banished as a whole,}}

===Ancillary material===
*According to complementary fiction released in the ''[[Halo Wars: Official Strategy Guide]]'', the Covenant had discovered [[Trove]] prior to the events of ''Halo Wars''.<ref>'''[[Halo Wars: Official Strategy Guide]]''', ''pages 50-51''</ref> The ''Halo Waypoint'' video series ''"The Halo Wars Story Retold"'' instead claims that the Covenant discovered the shield world from data gathered at the [[Arcadia Forerunner ruins|Forerunner ruins on Arcadia]]. The version given in the game guide (ostensibly written by the game's writers as background fiction to flesh out the characters) is seemingly supported by the in-game story: the first scene showing the Covenant on the shield world does not give any indication that the shield world is a recent discovery, only serving as the backdrop for the Prophet of Regret and the Arbiter's conversation about the events on Harvest and Arcadia.<ref>'''Halo Wars''', campaign level ''[[Scarab (level)|Scarab]]'' (opening cinematic, ''"Walk in the Park"'')</ref>

*In the second [[Data Drop]], [[Michael Stanforth|Vice Admiral Stanforth]] states that several cities on [[Sigma Octanus IV]] ([[Caracas]], [[Huiren]], [[Côte d'Azur]], [[Silma]] and [[Enfield]]) were destroyed during the [[Battle of Sigma Octanus IV|battle for the planet]]. ''Halo: The Fall of Reach'' explicitly states that most of the planet was spared with fighting only in and around Côte d'Azur.<ref>'''Halo: The Fall of Reach''', ''page '' (2001) ''page 243'' (2011)</ref>

*According to ''[[Halo 4: The Essential Visual Guide]]'' and {{Plain|[https://www.halowaypoint.com/en-us/universe/characters/carlo-hoya his biography on Halo Waypoint]}}, [[Carlo Hoya]] was born on [[Asmara]] in [[2533]]. However, [[Data pads|data pad 14]] in ''[[Halo: Reach]]'' indicates that Asmara had been glassed by the end of [[2529]].

*''[[Halo: Official Spartan Field Manual]]'' incorrectly lists the [[Battle of Installation 00]] as taking place in [[2552#November|November, 2552]], when the battle actually happened on [[2552#December|December 11, 2552]].<ref>'''Halo: Official Spartan Field Manual''', ''page 104''</ref>

===Multiple sources===
''Conflicts which involve more than two sources are listed here.''

*All pertinent media released since 2009 state that 25 of the 28 active Spartan-IIs still assigned to NAVSPECWEAP (from an initial unit of 33)<ref>'''Halo: The Fall of Reach''', ''page 60''</ref> were summoned to Reach for [[Operation: RED FLAG]].{{Ref/Note|These media include the ''Halo Wars'' timeline, the revised versions of ''The Fall of Reach'' and ''First Strike'', (including Fred-104's psychological evaluation in the Adjunct), the {{Plain|[http://youtu.be/jh7Q3fjIIwc ''Defiant to the End'' trailer]}}, the [[Data Drop]], the ''Halo: Combat Evolved Anniversary'' [[Library (feature)|Library]], and ''[[Halo: Fall of Reach - Covenant]]''.}}{{Ref/Note|This count does not include the four-member Black Team, whose survival was kept secret from their peers, as they operated under the Office of Naval Intelligence rather than Naval Special Weapons. During the early stages of the invasion of the Epsilon Eridani system, Black Team participated in the [[Battle of Verge]] and possibly the concurrent [[Battle of Tribute]].}} The three absent Spartans were [[Gray Team]], who had been out of contact since [[2551]].

:Two Spartans (including [[Oscar-129]]) committed suicide after escaping the program in mid-[[2525]].<ref name="HC">'''Halo Legends''', ''[[Homecoming]]''</ref> [[Samuel-034]] became the first Spartan to be killed in action in November 2525. At some point in the early years of the war, [[Jerome-092]], [[Douglas-042]], and [[Alice-130]] (all of whom had "washed out" by failing to adapt to their augmentations) were retrained, re-augmented, and placed into active service,<ref name="Alice PL">''Halo Wars 2'' - [[Phoenix Logs#Alice-130|Phoenix Logs, Alice 130]]</ref> bringing the total number of active Spartan-IIs back to 33. [[Daisy-023]]{{Ref/Reuse|HC}} and an [[unidentified Spartan-II]] were killed in early [[2531]]. Jerome, Douglas, and Alice went missing in action in February 2531; they were stranded outside UEG space aboard {{UNSCShip|Spirit of Fire}}, which was declared lost with all hands in [[2534]].{{Ref/Reuse|hwtimeline}} In November 2531, [[Kurt-051]] was abducted by the Office of Naval Intelligence to lead the [[SPARTAN-III program]]. [[Randall-037]] went MIA on [[Vodin]] in [[2532]] and secretly returned to civilian life, though Dr. Halsey considered him truly missing.

:[[Cal-141]] was killed on [[Heian]] in the early [[2540]]s.<ref>See [[Raid on Heian#Note|here]].</ref> Three Spartans were killed in action between [[2542]] and [[2552#August|August 29, 2552]]:{{Ref/Reuse|TFoR casualties}} [[Sheila-065]] died on [[Miridem]] in [[2544]], while [[Solomon-069]] and [[Arthur-079]] were killed during [[Operation: WARM BLANKET]] shortly thereafter.<ref>''[[The Package (animated short)|The Package]]''</ref> Another Spartan was too heavily wounded to continue active duty in this time frame.<ref name="TFoR casualties">'''Halo: The Fall of Reach''', ''page 240''</ref> [[Jorge-052]] fought during the Fall of Reach, though he served with [[Special Warfare Command|Army SPECWAR's]] [[NOBLE Team]] rather than being recalled for Operation: RED FLAG; however, it is possible that Jorge being the wounded Spartan was a cover story for his reassignment to NOBLE Team. By this count, no more than 20 Spartan-IIs could have been present for Operation: RED FLAG, with the possibility that Jorge and the wounded Spartan are synonymous bringing the number to 21.

**In [[Dr. Halsey's personal journal|her journal]], [[Dr. Catherine Halsey]] expressed her hope that [[Kirk-018]] and [[René-081]], two of the twelve crippled "washouts", could be rehabilitated and returned to active duty; she further noted that experimental rehabilitation protocols were in development for 80% of the washouts and that AIs predicted a total survival rate as high as 50%.<ref>'''Dr. Halsey's personal journal''', June 27, 2525''</ref> Jerome-092, Douglas-042, and Alice-130 were eventually rehabilitated and placed on active duty by February 2531.{{Ref/Reuse|Alice PL}} [[Soren-066]] escaped the program in 2526, having unwittingly joined the [[Insurrectionist]] cause; Halsey refused to bring him back into the fold against his will and he presumably died afterward. [[Ralph-103]] was discharged due to psychological problems and his augmentations were curtailed; he later joined the Marine Corps and was killed in 2531. The wheelchair-bound [[Fhajad-084]] became an ONI data analyst. [[Maria-062]] retired sometime before October 2552, though she was still capable of using Mjolnir powered armor.<ref>'''[[Halo Graphic Novel]]''', ''[[Armor Testing]]''</ref> [[Cassandra-075]] was still undergoing skin grafts as of October 2552. [[Musa-096]] also became wheelchair-bound and was responsible for developing the [[SPARTAN-IV program]] by January 2553. In addition to Jerome, Douglas, and Alice, this leaves three washouts who were potentially rehabilitated and returned to active duty, which could increase the number of Spartans at Reach to as many as 24.
**Dr. Halsey refused to allow invasive autopsies on the deceased Spartan candidates' bodies and arranged a closed-casket funeral; the coffins were empty and the bodies were actually placed in cryonic storage. She feared what ONI would do with the candidates' cadavers, suspecting that they would form their own, secret Spartan unit; indeed, this is presumably how the four-member [[Black Team]] came under ONI's command. Given that Halsey resurrected Linda-058 from clinical death with the rather limited facilities aboard the {{UNSCShip|Gettysburg}}, it is possible, though very unlikely, that the Spartan-IIs' numbers were bolstered by some of their once-clinically deceased comrades.
***Although the other Spartan candidates were told that [[Serin-019]] had died, in reality she survived in spite of rejecting most of the augmentations. She was withdrawn from the program before the washouts' closed-casket funeral and was later reassigned to the Office of Naval Intelligence as CINCONI [[Margaret Parangosky]]'s personal attache.{{Ref/Reuse|Halo page 82}} It is possible that other Spartans (such as the aforementioned Black Team) were likewise falsely reported as dead.
**''[[i love bees]]'' depicts a second class of Spartan-IIs that was launched around [[2537]], though this class has not been referenced in subsequent media. Assuming the second class is still canonical, the original Spartans' numbers may have been bolstered with later Spartan-IIs.

*In ''Halo: The Flood'', the [[D77-TC Pelican]]'s operational capacity is said to support a pilot, a copilot, a crew chief, and 12 passengers in the troop bay.<ref>'''Halo: The Flood''', page 76</ref> According to the ''Halo: Combat Evolved'' strategy guide, the Pelican can operate with three crew members, ten seated passengers, and five standing passengers.<ref>Sybex PC Guide, page 66</ref> In ''Halo: The Flood'', Pelican ''[[Charlie 217]]'' carries 30 Sangheili in the troop bay in addition to the [[Rick Hale|human pilot]] and [[Zuka 'Zamamee|another Sangheili]] in the cockpit.<ref>'''Halo: The Flood''', ''page 211''</ref> In ''Halo: First Strike'', Pelican ''[[Bravo 001]]'' carries 22 Spartans, though the Spartans had removed all unnecessary equipment from the troop bay, including the seats, and were packed nearly shoulder-to-shoulder in the troop bay; ''[[Halo: Fall of Reach - Invasion]]'', which rather loosely adapts the story of Red Team's insertion from ''First Strike'', shows that the Pelican had an expanded bay and far more massive overall than normal Pelicans. Pelicans seen in-game feature ten seats and could easily accommodate around ten more standing passengers.<ref>[[:File:Troopers in Pelican.jpg|Army Troopers aboard a Pelican in ''Halo: Reach''.]]</ref>

*In many sources, such as ''[[Halo: Last Light]]'' and ''[[Halo Wars 2]]'', Spartan-IIs and Spartan-IIIs are regularly addressed by their first names by fellow UNSC personnel and even civilians. It is stated in ''Halo: The Flood'' that the Spartan-IIs' names are not common knowledge even within the military.<ref>'''Halo: The Flood''', ''page 90'' (2003 edition)</ref> Throughout [[Eric Nylund]]'s novels the Spartan-IIs and Spartan-IIIs alike are instead most commonly addressed only as "SPARTAN" followed by their numeric tag in professional contexts; references to the Spartans in the games follow the same format, along with the use of the phonetic call sign "Sierra" in some cases.

*The extent of the capabilities of [[Forerunner]] [[slipspace portal]]s has been depicted inconsistently across different sources, with several newer works introducing portals capable of transporting individuals across interstellar distances without the use of a starship. In ''[[Halo: The Thursday War]]'', the first source to depict this type of portal, [[Evan Phillips]] states that it is common for Forerunner portals to displace individuals to different planets.{{Ref/Reuse|ttw181}} Later in the novel, a teleporter on [[Trevelyan]] propels Jul 'Mdama over a distance of many lightyears, all the way to the [[Sangheili]] colony of [[Hesduros]]. Individual translocation across interstellar distances (or the broader implications of such technology) is never acknowledged in any prior source.{{Ref/Note|Portals allowing the transit of unshielded individuals across interstellar distances would logically render starships obsolete, at least in more trafficked routes where portals would be most likely established. Yet individual portal transit is never mentioned in ''[[The Forerunner Saga]]'', which deals extensively with the Forerunners and their technologies, and Forerunners must still use ships to traverse their portal network.}} Given that the [[teleportation grid]]s on the [[Halo Array|Halo rings]], for example, are exclusively local systems (the teleportation grid on Installation 04 does not extend even to the nearby [[Threshold]]),<ref>'''Halo: Combat Evolved Anniversary''', ''[[Terminal (Halo: Combat Evolved Anniversary)|Terminal 7]]''</ref> logic would dictate that individual teleportation does not operate on an interstellar scale and that a starship is required to access the larger-scale [[slipspace portal]]s due to the dangers of long-term unshielded exposure to slipspace. In ''[[Halo: Ghosts of Onyx]]'', comparatively short-range translocation across [[Onyx]] causes severe nausea and disorientation to the characters;<ref>'''Halo: Ghosts of Onyx''', ''page 316''</ref> such effects are nowhere to be seen with later depictions of portal-based translocation. In ''Ghosts of Onyx'', it is also noted that slipspace travel to another star system would have taken some amount of time rather than being instantaneous, a fact that enables Dr. Halsey to deduce the survivors from Onyx never traveled across an interstellar distance when they entered the [[Trevelyan|shield world]] in the core of the planet.<ref>'''Halo: Ghosts of Onyx''', ''page 381''</ref>

**Individuals traveling interstellar distances instantaneously via portals are later featured in ''[[Halo: Escalation]]''<nowiki>'</nowiki>s ''"The Next 72 Hours"'' story arc and ''[[Halo: Spartan Strike]]'', suggesting that this may represent a universal retcon regarding the Forerunners' translocation capabilities. Alternatively, it is possible that interstellar teleportation was possible only to a limited extent or under specific circumstances, but not regularly practiced due to possible issues with safety or reliability. Notably, all known instances of individual portal transit are based on Forerunner military installations; [[shield world]]s and [[Halo]]s, while the portals in ''Spartan Strike'' are related to the special artifact known as the [[Conduit]].

*In ''The Package'' and ''Halo 4: Forward Unto Dawn'', Kelly-087 speaks with a General American accent. In ''Halo: The Fall of Reach - The Animated Series'' and ''Halo 5: Guardians'', she speaks with a British accent. According to 343 Industries, the latter should be considered the definitive portrayal of the character, with the prior ones regarded as artistic license.<ref>[https://www.halowaypoint.com/en-us/news/canon-fodder-know-for-an-answer '''Halo Waypoint''': ''Canon Fodder - Know for an Answer'']</ref>

*In [[Halo: First Strike]],<ref>Halo First Strike, page 240</ref> it is clearly stated that [[Eridanus II]] was a colony destroyed by the Covenant on 2530, and this fact is referenced various times in the novel. In [[Halo: Warfleet]], however, it is stated that "The planet's urban areas were destroyed at the end of the Covenant War, but enough population and infrastructure survived to ensure Eridanus II was selected for priority redevelopment".<ref>Halo Warfleet, page 22</ref> Even though it's possible that the Covenant gave back the colony at some point, just to return at a later date and glass it a second time, this is probably just a mistake.

===Written works vs. visual media===
*According to ''Halo: The Fall of Reach'' and ''First Strike'', the Spartan-IIs wore identical Mjolnir armor which lacked any identifying features, making it nearly impossible for an outsider to tell them apart; Dr. Halsey distinguished the Spartans only by the subtleties of their movement.<ref>'''Halo: First Strike''', ''page 120-121''</ref> However, in later visual media they are shown displaying their numeric tags on their armor and wearing specialized Mjolnir variants. At least five Spartan-IIs (Jerome, Douglas, Alice, Cal, and Kelly) even had pinup art painted on their Mark IV suits.
**Such distinction is all but necessary in a visual medium, as making the Spartans superficially identical would no doubt confuse the audience. While the Spartans could distinguish one another by body language, having their tags displayed could benefit any non-Spartan personnel they served alongside. The reason behind the Spartans' use of armor variants is more obvious: forgoing their use would be out of character, particularly for specialists who could make use of [[Wikipedia:Military Occupational Specialty|MOS]]-intended models. From a production standpoint, this is because ''The Fall of Reach'' and ''First Strike'' were released before ''Halo 3'' introduced the concept of purpose-built armor permutations.

*In [[Eric Nylund]]'s books Dr. Halsey is often said to wear glasses, habitually pushing them up her nose. In each of her visual appearances (with the exception of ''Homecoming'') Halsey does not wear glasses, while the ''Kilo-Five Trilogy'' simply makes no mention of them. The novels also frequently describe Halsey as having her hair tied to a bun,<ref>'''Halo: The Fall of Reach''', ''page 15'' (2001)</ref><ref>'''Halo: First Strike''', ''page 119'' (2003)</ref> which is never portrayed in visual media; she is instead most often depicted as sporting a hairstyle roughly similar to that of Cortana in ''Halo 3''.

*In all of its visual appearances [[slipstream space]] is depicted as having some form of visible effect to it, often a blue-tinted tunnel. In all written media slipspace is established as being a nonvisible inky void, barring the anomalous slipspace pocket generated by the [[Forerunner crystal]] in ''[[Halo: First Strike]]'' which caused a number of ships to be trapped in a slipspace bubble resembling blue fog. Presumably, the visual depictions of slipspace are concessions to visually convey the movement of ships traveling in the alternate domain.

*In the novels, it is common practice within the UNSC for individuals to enter [[cryo chamber|cryosleep]] naked due to the risk of intense blistering and pain caused by clothing adhering to the skin.<ref>'''Halo: The Fall of Reach''', ''page 14'' (2001)</ref><ref>'''Halo: The Flood''', ''page 20'' (2003)</ref><ref>'''Halo: Contact Harvest''', ''page 63''</ref> In ''[[Halo Wars]]'', ''[[The Package (animated short)|The Package]]'' and ''[[Halo 4: Forward Unto Dawn]]'', individuals are shown entering cryo fully clothed. ''Forward Unto Dawn'' introduces dedicated skintight bodysuits for use by personnel in cryo; it is possible that the atypical clothing worn by Dr. Halsey in ''The Package'' is meant to function in a similar way, although [[Ellen Anders]] is wearing her normal civilian clothes when entering cryo in ''Halo Wars''. In any case, the omission of nudity from scenes involving cryosleep is obviously a case of artistic license for content rating reasons.

*The size of the explosions produced by [[HAVOK tactical nuclear weapon]]s varies considerably throughout ''Halo'' media. For individual examples, see [[HAVOK tactical nuclear weapon|here]].

==Notes==
{{Ref/Notes}}

==Sources==
{{Ref/Sources|2}}

[[Category:Lists|inconsistencies in the Halo series]]