Turretless vehicle glitch
From Halopedia, the Halo wiki
The Turretless Vehicle Glitch is a glitch present in Halo 3's Forge. The glitch typically removes vehicles' armaments and prevents them from boosting.
When you perform this glitch, the vehicle is still drivable (except the Gunner position). However, the only consequences are that the vehicles would be defenseless due to removal of their armaments. This, of course, makes this glitch more popular with machinima creators than with players. If a person drives one of the vehicles without its armament, they would be able to see the weapons being fired, though no one else can and the shots would do no damage.
Instructions
In Forge, enter Edit Mode and bring up the object menu by pressing X. Scroll to the Vehicles category, and move the cursor over whichever vehicle you wish to perform the glitch on. Get the party leader to start a new round. Just after "Round over" is heard, the screen will fade to black, and the menu will stay up for several seconds after "Round over" was uttered.
As soon as the screen goes completely black, spawn the vehicle -- if you spawn the vehicle too early, it will spawn normally, but if you wait too long, the menu will close automatically. When the new round has started, go to the spot that you were previously standing. The turret-less vehicle should be in the position you spawned it in. The vehicle will only remain in its turret-less state for that particular round.
If you start a new round, end the game, or save the map with the turret-less vehicle and load it again in Forge or in a Custom Game, the vehicle will be in its normal state.
The ability to perform this glitch may be related to the number of people in the party. It doesn't appear to work with only one person in the party, because the object menu disappears when you start the new round. The connection speed may also play a role, as both perfect and laggy connections tend to prevent the glitch from occurring.
Effect
Warthog/Prowler
The vehicles lose their turrets. Warthogs gain a resemblance to Civilian Warthogs or Flatbed Warthogs.
Scorpion/Wraith
The vehicles lose their cannons and turrets. Scorpions that have been glitched in such a manner tend to be nicknamed "Armored Personnel Carrier" or "Turtles". The alterations made to Wraiths are quite striking, as the mortar launcher comprises a large portion of a Wraith's rear.
Mongoose/Ghost/Chopper
Cannons, the Mongoose's horn, and boosts have all been disabled.
Banshee/Hornet
Weapons and boosts have been disabled. Hornets gain a resemblance to Transport Hornets.
