List of inconsistencies in the Halo series

This list is compiled to show the various discrepancies spotted in the Halo universe. It is difficult to decide which resource is "superior" to another, so usually, the inconsistency is mentioned in the articles that it involves.

If you think you can explain an inconsistency, do so here, on this article's talk page.

There are two types of inconsistencies: Conflicts and Discrepancies. Conflicts happen when two sources disagree about a situation, subject or object. Discrepancies occur when a seemingly impossible event happens without any explanation.

Halo: Combat Evolved

 * The main view screen on the Pillar of Autumn labels the as-of-yet unidentified ring as "Halo". The name of the ring is not discovered until the level The Truth and Reconciliation.
 * Cortana says she cannot begin to calculate the pulse range of Halo just after 343 Guilty Spark finishes telling her it has a radius of exactly 25,000 light years.
 * This can be accounted for by Cortana's inherent distrust of Guilty Spark's motives. Additionally, since Cortana is an 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 simply told her.
 * She did not state she wanted to know the range, she simply stated she cannot calculate it.
 * Almost every Pelican dropship bears the marking of Foehammer's bird, "E419", on its side, despite the fact that each Pelican has a different serial number.
 * While there is no canon explanation, this is due to the fact that only two Pelican models, V933 and E419 are 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 3 kilometers atop the Pillar of Autumn to reach the Longsword fighter, but the Autumn is only 1.17 kilometers long.
 * The Longsword's launch bay in The Maw 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 travelled from side to side. This makes even less sense than the Autumn suddenly being two kilometres longer.
 * During the level Assault on the Control Room, Staff Sergeant Johnson can be seen with the Chief at the time he was really with Captain Keyes searching for the Covenant's "weapon cache"; even though the Captain has been out of reach since The Silent Cartographer.
 * This is ostensibly a result of Bungie was reusing Johnson's model instead of creating another Sergeant model.
 * In 343 Guilty Spark, when John-117 arrives at the room, he finds Pvt. Jenkins' mission recording. As he opens the door a body collapses on him. It is unclear as to why this body was not infected when the Flood overran the marines in the room.
 * This was likely done simply to add tension and suspense to the level.

Halo 2

 * In the video "Another Day at the Beach", the UNSC forces that land near Hotel Zanzibar wear ODST armor. 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.
 * Also, on the Halo 2 case, the back depicts Master Chief fighting alongside ODST troops on Earth, whereas in the game, ODSTs are not present until the level "Delta Halo."
 * In the level Delta Halo, you can find dead ODSTs all around the level -- 7 to be exact. However, In Amber Clad only dropped 11 HEVs in the opening cinematic. 3 ODSTs, the Master Chief, 3 more dead, and the seven ODSTs makes 14 dead soldiers. This may just be a secret 7 reference, however, as 7=7 and 7x2=14.

Halo 3

 * Every Longsword fighter bears the marking 7-89 on its side, despite that each Longsword has a different serial number. This is likely the result of reusing the same model.
 * 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"; one of the others is the Aegis Fate. This is also obviously the result of reusing the same model.
 * In the ending cutscene of the level Halo, the Arbiter is shown sitting down on the bridge 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, 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 Wars
In the level Dome of Light, after requesting the first Rhino to be deployed, the radio operator on the will identify the player as "Harvest Surface Command" even though the level takes place on Arcadia.
 * This could be that the Spirit of Fire was still assigned to Harvest.

Halo: The Fall of Reach

 * The Eridanus II space dock is erroneously stated to be located in the Epsilon Eridani system in the chapter heading for Chapter 10. Throughout the rest of the book, Eridanus II is correctly referenced as being located in the similarly named, yet distinct, Eridanus system.


 * During Master Chief's mission to Reach Station Gamma, a Jackal's blood is said to be blue, although it is clearly purple in the games. The same mistake is made with the Elites, saying that their blood is green, while it too is purple.


 * The book describes Lt. Hikowa as male, but then later refers to the lieutenant as female. This is fixed in later printings.

Halo: The Flood
At one point, the book states: "Consistent with his status as a veteran, the first alien to come around the corner wore red-trimmed armor, a methane rig, and a Marine's web pistol belt. The alien wore the captured gear Pancho Villa-style and dragged it across the deck. Two of his comrades brought up the rear." That is three Grunts in the Master Chief's sight. The next paragraph says, "Confident that there were more of the vaguely simian aliens on the way, the Master Chief paused long enough to let more of them appear, then opened fire. The recoil compensators in his armor dampened the effect, but he could still feel the handgun kick against his palm. All three of the Grunts went down from head shots." It is as if the extra Grunts that appeared simply disappeared. Only three Grunts were killed, which are the three original Grunts that first appeared: the leader and the two followers. But "...the Master Chief paused long enough to let more of them appear, then opened fire... All three of the Grunts went down from head shots." It is possible, though, that the Master Chief had simply expected more Grunts to appear; he may have simply waited in case more Grunts appeared, and then opened fire when he was sure there were not any. It is also possible that Master Chief was simply waiting for more of the three Grunts to appear, giving him larger target silhouettes to hit.

''Halo: First Strike
In Chapter 33, it says 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.

Halo: Ghosts of Onyx
Kurt's rank was apparently lieutenant commander in 2545, as said in the prologue. However, he was still referred to as a lieutenant by 2551 later in the story.

Halo: The Cole Protocol
When Lieutenant Keyes is warned of the incoming Covenant fleet and asks what UNSC ships are nearby, the book first states that three destroyers are picketing, but immediately counters that the and three frigates wouldn't be able to repel a Covenant assault. However, they are later confirmed to be destroyers, one of which is the.

Halo: Fall of Reach

 * When the Spartans are issued their MJOLNIR Mark IV armor, the armor is free of any insignia. After suiting up, the armor now has the SPARTANs' tag on the chest.
 * When Halsey puts on John's helmet for him, the helmet in her hands resembles the Mark VI's, with its raised brow, center oval groove, and square mouthguard. In the next page as John wears the helmet, it now is the default Mark IV's, with its lowered brow, sleeker shape, and large breathing ports.
 * The bonus layout artwork for Covenant shows the Spartans wearing The Package Mark VI-looking armor in the initial sketches, then being corrected to Halo Wars 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.
 * During the skirmish between the Unrelenting and the, 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 inside 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 it's the first one they encountered.
 * During the raid of the, the captain tells her men to brace themselves before firing their guns in zero-g, as the equal and opposite reaction will push them backwards. The cover for Issue 2 of Covenant shows John standing on the outside of the Unrelenting firing in, and not having any trouble with his gun's recoil in zero-g.
 * 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.

Halo 4
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 he is only minutely taller than her while in the Epilogue he towers over her by about two feet.

Conflicts
''For the sake of convenience, most conflicts are listed under the piece of media which introduced the conflict. Conflicts which are persistent throughout multiple sources are listed in the "General" section.''

Halo: Combat Evolved manual

 * The Halo: Combat Evolved manual states that the Harvest incident took place in 2520, while all other sources specify 2525.
 * The manual also states that Captain Keyes has served in the UNSC since 2526, though he was fresh out of the UNSC OCS in 2517.
 * The Grunts are referred to as being five feet tall in the Halo: Combat Evolved manual, but in The Fall of Reach, they are referred to as being a meter tall (a little over three feet). Although it could be that Grunts are "a meter tall" in a natural combat stance, while they are actually "five feet tall" if they stand up straight, without a methane tank attached to their backs.
 * According to the manual, the Covenant attacked Reach two days before the Spartans' 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 describes the as being a colony ship. The ship was said to be a frigate in Halo: The Fall of Reach.

Halo: The Fall of Reach

 * 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, the bridge has no female members.
 * This may imply that, like modern navy ships, the Autumn has rotating shifts.


 * William Lovell's eyes are stated to be green in Halo: The Fall of Reach, 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, 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. 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, 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. The ship is also described as having rotating centrifuges to generate artificial gravity; no rotating sections are present in the game, unless they are located within the hull.


 * 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, yet the gun is apparently used, and the loss of fire control is treated as a significant piece of dialogue in Halo: Combat Evolved's opening cutscene.
 * It is possible that the crew managed to get the gun working again before the battle.

Halo: The Flood

 * In Halo: The Fall of Reach, Lieutenants Hall and Dominique are introduced as members of the command crew of the Pillar of Autumn, but are absent in Halo: The Flood when the ship arrives at Installation 04. It should be noted, though, that Halo: The Fall of Reach states that there was a flutter in Dominique's heart when he came out of cryo-sleep prior to the discovery of Alpha Halo, perhaps indicating cardiac arrest. It is also possible that they were simply not present on the bridge due to rotating shifts.


 * In Halo: The Flood, the presence of the Covenant at Installation 04 is regarded as being 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, or by chance. 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.


 * In Halo: The Flood, Captain Keyes comments that a single plasma torpedo is capable of destroying the Pillar of Autumn, though in Halo: Combat Evolved it is struck by several without losing structural integrity and breaking up.
 * This possibly relates to the Minor Prophet's order to not fire plasma torpedoes. Additionally, the Covenant ships may have chosen to fire undercharged shots to minimize damage to Halo caused by stray shots.


 * In Halo: The Flood, Cortana identifies Installation 04 as "Halo" in Halo: The Flood when escaping the Pillar of Autumn, but in Halo: Combat Evolved, it is not identified by this name until the 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. 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, 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.


 * 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 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. In the game, there are two Special Operations Elites on the elevator and no Shade turret. In addition, Cortana does not move the elevator.


 * 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.


 * In Halo: The Flood, 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; 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". 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, but in Halo: The Flood, 343 Guilty Spark was regarded as an enemy by the Sangheili.
 * This is probably because the fiction regarding the Covenant's beliefs had not yet been cemented by the time The Flood was written.

Halo: First Strike

 * 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. However, in Halo: The Fall of Reach, she called him "Master Chief" repeatedly.


 * 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. 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. It is possible that the magnetic controls were not destroyed in the former instance, allowing the plasma to continue to its target.

Halo: Ghosts of Onyx

 * In Halo: First Strike, Dr. Halsey puts four M7/Caseless Submachine Guns in a bag. In Halo: Ghosts of Onyx, Kelly found the same weapons, but they were four MA5B Assault Rifles instead.


 * In Halo: Ghosts of Onyx, Kurt-051 remarks that some of the Alpha Company candidates were orphaned at Jericho VII. His speech takes place on December 12, 2531, yet Jericho VII was not glassed until February 2535.
 * 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 somewhat similar to how the Covenant initially invaded Arcadia in 2531 but only arrived to glass the planet eighteen years later.


 * On page 129 of Halo: Ghosts of Onyx, Franklin Mendez was mentioned to be "pushing sixty [years old]", which implies that his birthdate is close to or after 2493. However, this would give him a maximum age of 24 when he started training the SPARTAN-IIs, which is unlikely given his description of "grey hair at the temples" and "having seen much combat" as well as his high rank of Chief Petty Officer. In Halo: Glasslands, Mendez is also mentioned as being the same age as Dr. Halsey, who is sixty at the time.

Halo: Contact Harvest

 * 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 population is also listed as three million in Halo: Fall of Reach - Boot Camp and Halo: The Essential Visual Guide.


 * Throughout Halo: Contact Harvest, the Eridanus and 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. With two exceptions, (a chapter heading in the first printing of Halo: The Fall of Reach 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.


 * In Halo: Contact Harvest, humanity is said to have seventeen planetary colonies. In a 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, (as well as the pre-release Halo: Combat Evolved timeline), have ignored Staten's claim, showing that the Unified Earth Government had, at the very least, several dozen developed colony planets and had some presence on over 800 worlds.

Halo: The Cole Protocol
In Halo: The Flood it says Captain Keyes killed his first human with a pistol, which was specifically stated to have a barrel; however, Halo: The Cole Protocol states he used a modified plasma rifle, a weapon which lacks any form of barrel.

Halo Wars

 * Although the Forerunner 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 "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 OF-92 Booster Frame.

Halo 3: ODST

 * 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 was in Halo 2.


 * In Halo 3: ODST, the Solemn Penance is seen as being stationary just prior to it jumping into slipspace, yet in Halo 2 during the closing cutscene of the level Metropolis, the assault carrier is moving forward.
 * During the same scene in Halo 3: ODST, the 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.


 * In the profiles for the members of the squad, it is shown that Kojo Agu enlisted in the UNSC when he was only 17 years old, after serving as a merchant marine. As shown in i love bees and later Halo: Glasslands, the minimum age of enlistment for the UNSC is 18 years.
 * It can be assumed that an exception was made for Agu, as it is noted he was retained on service for actions that normally would get a trooper discharged.

Halo: Evolutions - Essential Tales of the Halo Universe

 * In The Mona Lisa, it is repeatedly stated that the UNSC had a "policy" not to take Covenant prisoners and the main characters are shown to be baffled about discovering Covenant prisoners aboard the prison vessel Mona Lisa. 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 a strictly enforced protocol.


 * 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 corporate building instead of a hotel. In the game, it is mentioned that the Marines' lieutenant was killed as soon as they arrived and that Sergeant Banks is in charge at the time, while in Palace Hotel, John meets the Marines' lieutenant at the outpost.


 * In Human Weakness, Cortana knows about the death of Colonel James Ackerson while being held captive by the Gravemind in High Charity. There is no way she could possibly have been aware of the event at this point, as Ackerson was killed after the Battle of Cleveland sometime between November 8 and 17, and the scene in High Charity takes place days prior. Even accounting for the possibility she may have somehow learned this immediately after Ackerson was executed, she refers to the event in a fashion as if she had been aware of it beforehand.


 * In The Impossible Life and the Possible Death of Preston J. Cole, it is clearly stated that Vice Admiral Preston Cole had 117 ships under his command during the Battle of Alpha Aurigae. Halo Wars: Genesis states he had only 107 ships in the same battle. The revised number is an obvious reference to John-117, so it could be considered an Easter egg.


 * According to The Impossible Life and the Possible Death of Preston J. Cole, two of Preston Cole's grandfathers served in the Rain Forest Wars. This seems unlikely, as the conflict took place over three centuries before Cole's birth.


 * 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 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. Nonetheless, the ONI memorial in Halo 3: ODST refers to him posthumously as a full admiral.


 * In The Impossible Life and the Possible Death of Preston J. Cole, 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 by class at Arcadia in 2531; data pad 10, which states that the Assembly's findings about glassing were derived from observing the CCS class in 2526; and Halo: The Essential Visual Guide and the Halo Encyclopedia, which state that vessels of the class were encountered frequently throughout the war.

Halo: Reach

 * In Halo: Combat Evolved, as well as 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.


 * According to an Intersystem News sheet that comes with the Limited and 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 July 2552.


 * The placement of the multiplayer map Breakneck in New Mombasa appears to be inconsistent with the city's Halo 3: ODST incarnation. Assuming the locations of the city's landmarks, such as the bridge of the Uplift 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. 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.

Halo: Fall of Reach

 * In Issue 1 of Boot Camp, Vice Admiral Ysionris Jeromi sends Halsey his results on the SPARTAN-II augmentation procedures just after children were kidnapped in 2517. In the book, he sent the results in 2525, just before the surgeries began.
 * Kelly-087 is depicted with a bob cut hairstyle during childhood training. In Dr. Halsey's personal journal, Kelly is drawn having her head shaved, with an entry mentioned how she had to be held down for the barbers to finishing cutting her hair.
 * The first transmission from the Covenant to humanity that tells them their destruction is the will of the gods is an audio message in the novel. In the comic it is a video, with the Prophet of Regret personally appearing to announce it to them.
 * In the book, Blue Team's fight with the Hunters in the Côte d'Azur Museum of Natural History is won by using shredder rounds to break the floor beneath their feet then pushing a stone monolith into the hole to crush them. In the comic, the battle is won by using two grenades to crack the monolith then breaking it so that the upper half falls and crushes the Hunters.

Halo: Glasslands

 * Captain Osman claims that the UNSC had captured and defused a Huragok "a couple of years ago", and that ONI made several technological developments by reverse-engineering the data it contained. She implies that the Engineer had died and states that ONI needs more than one Huragok so they can repair each other and reproduce. Strangely, she does not mention that several Huragok were rounded up aboard the when it returned to Earth, nor does she say that one was rescued from New Mombasa and interrogated shortly thereafter. It is possible that she refrained from telling the "whole truth" to motivate her team to board Piety and capture the Engineer onboard.


 * According to Halo: Glasslands, Dr. Halsey did not have an AI to help her decipher Forerunner symbols while in the shield world. 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. No mention was made of Halsey losing Jerrod, and she still had her laptop after she and the other survivors had entered the shield world.


 * When the survivors in the shield world reestablish contact with the UNSC, 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. However, John and Cortana disappeared on December 11, 2552, with the UNSC receiving confirmation of this when the Arbiter returned to Earth on December 23. The scene with Parangosky informing Halsey about their disappearance occurs in February 2553, so less 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 - less than four months earlier - in which she announced that John was on his way to Earth.

Halo: The Thursday War

 * The carries a large arsenal of nuclear weapons onboard and is yet capable of remaining completely undetected over Sanghelios. 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 stealthed slipspace exit.


 * It is implied that Dr. Halsey's involvement with smart AI development stopped after her extensive work with third-generation smart AIs; she is shown to be 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. 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 Zen koan to attract the attention of Endless Summer and states that fifth-generation smart AIs like to "show off". In addition, the fact that Endless Summer and its predecessor, Deep Winter, were fifth-generation smart AIs, implies that the fifth generation had already gone active circa 2544, around the time when Deep Winter would have entered service. Given how Cortana, an AI personally created by Dr. Halsey, was considered incredibly advanced by 2552, she would have certainly been considered to be at least of the same generation as Deep Winter or Endless Summer, both of whom had the comparatively simple assignment of overseeing ONI's operations on Onyx.
 * It is possible that Halsey may have 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, but he appears to regard Halsey's ignorance about the development of fourth-generation AIs such as himself as a fact.

Halo 4

 * In the Prologue cutscene, many inconsistencies are shown. It is implied that Halsey is imagining most of the cinematic's visuals, but this does not solve problems like how all the SPARTAN-IIs were wearing John's modified MJOLNIR Mark VI, which she has never seen.
 * In John-117's accessible service record in the level Dawn, the Pillar of Autumn is misidentified as a frigate.
 * Cortana is said to have used nano-machines to repair John's armor while in cryo, but despite almost completely changing its design the suit retains a gash on its right side received from John's free-fall drop in Halo 3.
 * Since John's full armor is never seen until the opening cutscene of Requiem, it is possible that the gash was indeed repaired only for the suit to be damaged again after John fell into the shield world.
 * Despite maintaining a generally similar profile, Halo 4 ' s incarnation of Forward Unto Dawn is noticeably different from its appearance in Halo 3. The ship appears much larger, with more of the forward half remaining intact, though the ship is still canonically 490 meters long. The number of engines has been reduced; rather than having two primaries on the main hull and two secondaries on the "wings", there are only two primary engines. The port and starboard hangar bays have been reduced from five small bays on either side to one much larger bay on either side; they are moved much farther back, remaining with the aft section. The enlarged cargo bay, a defining feature of the Charon class, is conspicuously absent or is at least moved inside the hull; either way, this creates an inconsistency with the final cutscene of the level Halo. The point defense guns have been retconned into two separate models, increased in number, and moved to different areas on the hull. The ship's cryo tubes have also been remodeled and the cryo bay has been rearranged.
 * From a production standpoint, the ship was enlarged to create a more dynamic and exciting playspace; the original model would have been very small and cramped, limiting the first level's gameplay potential. The more superficial changes, such as those made to the cryo tubes and the point defense guns, are intended to reflect Halo 4's more functional art style.
 * Halo 4: Forward Unto Dawn depicts a large UNSC fleet accompanying the Infinity to Requiem. However, when the Infinity arrives to the planet that escorting fleet is nowhere to be seen.
 * The fleet may have been sent to deal with the Covenant remnant ships still in orbit above Requiem.
 * The Composer is depicted as a terrifying superweapon that irreversibly corrupts anyone digitized by it. However, in Halo: Primordium, the Composer is much more benign, used even by the Librarian to preserve human minds for future study, those minds surviving the process and emerging intact. Halo 4 also portrays the physical effects of the Composer as much more gruesome, burning its targets to ash, whereas in Primordium those subjected to the Composer only experienced a relaxed sensation before expiring.
 * The Composer was used via intermediary Lifeworker machinery during the events of the novel, whereas it is used directly upon its targets in Halo 4; it is possible that this direct application is what renders the Composer so dangerous. Additionally, since the Composer is described as having a wide variety of capabilities, it is possible that the Lifeworkers chose to employ a gentler form of extraction while the Didact would have no qualms with using a more efficient and violent capability on his former enemies.
 * The Cryptum that preserved the Didact on Erde-Tyrene 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.
 * The Librarian is described as looking very youthful, and humans, such as Forthencho and Chakas, considered her beautiful, the former noting how her features had a "compelling beauty" and the latter describing her as "beautiful beyond measure". One result of her work with gei on humanity is that her image became what humans subconsciously view as the perfect female. In Halo 4, the Librarian looks and sounds elderly, though she retains an elegant beauty.
 * As Chakas' recollection of the Librarian was based on his experience of the Librarian's automated imprinting system providing him with a geas at infancy, it is possible that his memory of the Librarian may have been colored by the contemporary humans' legends and worship of her as a goddess. In addition, her geas would have automatically caused any humans affected by it to consider her beautiful, regardless of what preferences the humans in question might have otherwise had. In a broader sense, it is implied that the Librarian's image of an ideal female has more to do with the subconscious idea of her rather than her physical appearance alone.
 * There is no mention in the Terminals of Halo 4 of the Didact's self-imposed exile or when he copied his personality into Bornstellar Makes Eternal Lasting. This is important because previous media showed the Didact had fired the Halo rings, which could not have happened if he were imprisoned in Requiem.
 * The Didact in Halo 3 ' s Terminals was heavily opposed to firing the Halo Array because it would be "murder. A genocide larger than this galaxy has ever known." However Halo 4 ' s Didact, while still opposed to the rings, has no qualms about using similarly genocidal weapons like the Composer; his opposition to using the rings revolves around maintaining the Forerunners' primacy rather than genuine altruism.
 * It may be that he draws the line at galaxy-wide genocide but views Composition as a smaller but necessary massacre. Additionally, this slaughter occurs after he has mutated from an experimental Flood cure he tested on himself, which is implied to have imbalanced his mind.
 * Slipspace is described as an entirely featureless, pitch-black void in most previous media; a direct result of its inherently "nonvisible" nature.   In the level Midnight, though, slipspace resembles a bluish expanse with white streaks of stars being flown past. Likewise in the opening cutscene of Departure slipspace appears as a kaleidoscope of colors. This may be from both ships using Forerunner slipspace engines, which have been observed to create differing environments.

Ancillary material

 * In Halo: Ghosts of Onyx, Frederic-104 is promoted to the rank of Lieutenant, Junior Grade near the end of the Battle of Onyx. However, the interrogation transcript featured in the Adjunct section of the 2010 edition of Halo: First Strike continuously refers to him as a lieutenant by the start of the Battle of Earth.


 * 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 here), no other source has referred to him as a fleet admiral.

Several sources
Conflicts which involve more than two sources are listed here.


 * All pertinent media released since 2009 state that twenty-five of the twenty-eight active SPARTAN-IIs serving under Naval Special Weapons were summoned to Reach for Operation: RED FLAG. All sources agree that thirty-three SPARTAN-IIs successfully adapted to the augmentations. Three Spartans were killed in action and one was too wounded to continue active duty in the decade between 2542 and August 29, 2552. Kurt-051 and Randall-037 were listed as missing in 2531; the former was kidnapped by ONI to lead the SPARTAN-III Program, while the latter was most likely killed in action. During the same year, Douglas-042, Jerome-092, and Alice-130 became stranded outside UNSC-controlled space, unable to contact allied forces, and were declared MIA in 2534. Jai-006, Adriana-111, and Mike-120 had been missing since 2551. SPARTAN-IIs confirmed KIA prior to the Fall of Reach include Samuel-034, Daisy-023, Sheila-065, Solomon-069, Arthur-079, and Cal-141. Maria-062 was stationed at Earth and worked with the Special Warfare Center in Seongnam; she claimed to have plans of starting a family. It is implied that Naomi-010 was not present at during the invasion of Reach. Jorge-052 fought during the Fall of Reach, though he served with Army SPECWAR's NOBLE Team rather than being recalled for Operation: RED FLAG. By this count, no more than sixteen SPARTAN-IIs could have been present for Operation: RED FLAG.
 * In 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. 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 soon afterward. Ralph-303 was discharged due to psychological problems and his augmentations were curtailed; he later joined the Marine Corps and died in 2531. Serin-019 was reassigned to the Office of Naval Intelligence as CINCONI Margaret Parangosky's personal attache, while Fhajad-084 became an ONI data analyst. Cassandra-075 was still undergoing skin grafts as of October 2552. Including Kirk and René, this leaves seven washouts who were potentially rehabilitated and returned to active duty, which could increase the number of Spartans at Reach to twenty-three, nearly resolving the numerical discrepancy.
 * 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. Given that Halsey resurrected Linda-058 from clinical death with the rather limited facilities aboard the, it is possible, though very unlikely, that the SPARTAN-IIs' numbers were bolstered by some of their formerly deceased comrades.


 * In Halo: The Flood, the D77-TC Pelican's operational capacity is said to support a pilot, a copilot, a crew chief, and twelve passengers in the troop bay. According to the Halo: Combat Evolved strategy guide, the Pelican can operate with three crew members, ten seated passengers, and five standing passengers. In Halo: The Flood, Pelican Charlie 217 carries thirty Sangheili in the troop bay in addition to the human pilot and another Sangheili in the cockpit. In Halo: First Strike, Pelican Bravo 001 carries twenty-two 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.

Inconsistencies rectified in re-releases
This is a list of disparities that remain in older novel editions, but have been retconned in later releases. For a complete list of changes in the re-releases, see here.

Halo: The Fall of Reach

 * In Halo: The Fall of Reach, the dropship used to transport the 75 SPARTAN-II children to the Military Wilderness Training Preserve was originally identified as a Pelican, whose troop bay would ostensibly be too small for 75 people. However, this was rectified in the 2010 reissue, in which the dropship is changed into a larger Albatross.


 * On page 46 of the original edition, Kelly handed out parts of a map to the seventy-five SPARTAN-II trainees. Then on page 48, when John checked to make sure the children arrived at the lake, he counted only sixty-seven...which seemed to be all of them. In the re-release, "sixty-seven" is changed to seventy-four.


 * In Chapter 22, James-005's left arm is burnt off by an assault cannon. In the original edition, it is said a few pages later that he saluted with his left hand–while it was still missing. In the 2010 re-release, he salutes with his right hand.


 * Captain Keyes refers to Ensign Lovell as "Michael" instead of "William". This has been fixed in the 2010 edition.


 * In the original, a UNSC frigate was referred to as the Alliance, and then shortly thereafter as the Allegiance. In the 2010 edition, the ship is referred to as the Allegiance in both instances.


 * In the original edition, the ship was referred to as a cruiser and then later as a carrier. In the 2010 edition, the ship is referred to as a cruiser in both cases.


 * On page 19, Michael Stanforth was said to be a Vice Admiral, and on page 95, it said he was a Rear Admiral. In the 2010 edition, he is referred to as a Vice Admiral in both instances.


 * The Pillar of Autumn was said to be missing its port-side emergency thrusters, but later used them twice. In the 2010 edition, the mention of the thrusters being missing has been removed.


 * In the original edition, the first time John-117 encounters Sangheili warriors in the battlefield is on Gamma Station during the Fall of Reach. In addition, the UNSC is depicted as not having any first-hand intelligence on the species prior to the battle; Dr. Halsey only speculates their existence. This has been largely ignored in later material, and Sangheili have been depicted as being present in battles throughout the war numerous times. References to the Sangheili as being a never-before-seen species were altered in the 2010 re-edition.

Halo: The Flood

 * The cutscene in Halo: Combat Evolved at the end of the level The Pillar of Autumn clearly shows the Autumn being fired upon with plasma. However, in Halo: The Flood, the Prophet assigned to the fleet forbids the Covenant ships to fire, lest they strike the "sacred relic". However, this is remedied in the fleet broadcast log in the ancillary content of the reissue of Halo: The Flood, where it is revealed that the order was ignored by the fleet's Supreme Commander.


 * The original edition describes how a group of entrenched Marines could not be hit by Ghosts' plasma fire, as the vehicles' plasma cannons were fixed and the marines were on a hill. In the games, the Ghost's plasma cannons can easily increase or decrease their angle. In the 2010 edition, the line is made more vague, stating the "Covenant vehicles couldn't get a fix on the Marines' position".


 * The original edition of the book consistently mistakes the 8-gauge M90 Shotgun as 12-gauge. This is corrected in the 2010 edition.


 * In the original edition, Sergeant Parker is consistently referred to as a he, and then a she. He is consistently referred to with the male pronoun in the new version.


 * In Chapter 9, the Second Squad was implied to have been completely consumed by the Flood, specifically saying that their numbers dwindled until two PFCs remained, before the last of the Marines fell. A page later, however, it is stated that there was little for Foehammer could do "except pick up the Marines, and hope for the best." In the 2010 edition, the part about picking up the Marines has been removed.


 * In Chapter 10 of the original version, it says that three weapons would be unwieldy for the Chief, not to mention "damned heavy." It then says he chose a shotgun and sniper rifle. During the ensuing engagement, it is then stated the Chief "switched to the pistol", despite the fact it was established he was only carrying a shotgun and a sniper rifle at the time. In the 2010 edition, "pistol" is changed to "shotgun".


 * In the original edition, First Lieutenant Melissa McKay's mission clock, seen in chapter headings, is prefixed by an extra 1, creating an inconsistency with the Master Chief's mission clock. This has been fixed in the 2010 edition.

Halo: First Strike

 * Similar to the inconsistency of the Spartans' first encounter with Sangheili, in Halo: First Strike, the Spartans did not have any prior knowledge of the Jiralhanae until their encounter with them on the Unyielding Hierophant during Operation: FIRST STRIKE. This has also been contradicted in multiple later works which show Brutes as being well known to UNSC forces throughout the war. Like the Sangheili encounter inconsistency in The Fall of Reach, in the re-release of First Strike, references to the Jiralhanae have been altered so that the Spartans are now familiar with them.


 * The Longsword used by the Master Chief and the other survivors from Installation 04 to land in the Ascendant Justice was repeatedly referred to as a Pelican in the original edition. The ship is consistently referenced as a Longsword in the reprint.


 * Vinh is referred to as "SPARTAN 029" twice in the original edition, even though the tag 029 is assigned to Joshua throughout the rest of the book. In the 2010 edition, Vinh is correctly referenced as "SPARTAN 030" in both instances.