Unlock New End Movie:
Beat the game on the Legendary setting to unlock a longer final movie.

Glitch: Skip FMV sequence:
On any level before a FMV sequence, throw a grenade. Most of the time the game will skip the FMV sequence.

Glitch: No head:
On the first level when you get out of the tube, press X when prompted to exit the cryo tube. Watch your character get out. The screen will be white and coming into view. After you take control finally, turn and jump in the cryo tube before it closes. When you get in and it closes with you inside, you are stuck. When you cannot move in the tube and look up in a certain manner you will see yourself, but with no head.

Glitch: Fall to death:
In level 5, the section "I Want To Be Your Daddy" is the first that you see. In order to do this trick you have to be in single player mode. When the Dropship is about to let you out, quickly press X button to sit back down in the seat. You will fly down the pit and go around in circles as the Covenant tries to shoot you down. Once you wait long enough, the Dropship disappears from sight and you will float down to your doom.

Glitch: Truth And Reconciliation: Forget Captain Keys:
As soon as you press X to lower the Covenant dropship, hurry and kill Captain Keys. Instead of showing the FMV sequence, the game will take you directly to the next level.

Glitch: The Maw: View screen:
When you get to the bridge and the FMV sequence starts, quickly skip it and the main view screen will still be there. If you watch the sequence, the view screen will be shattered and the Sentinels will have a clear shot at you. This is especially useful under the legendary difficulty setting.

Glitch: Silent Cartographer: Waiting for you:
Take the Warthog down to the floor where the door locks. Make sure you have marines in the Warthog. Park it in front of the door and leave them there. Do not go too fast before the door shuts, or your wheel will get stuck in the door. Play the game through until the FMV sequence showing the covenant swordsmen running out begins. He will run right into the warthog and start shooting. The marines will also shoot at him. However, when you go back the marines will still be there,and the swordsmen will occur later as normal.

Glitch: Assault On The Control Room: No enemies:
Kill the Covenant and get to the first bridge. Get to the lower level of it and at the side closest to the entrance, fall onto a nearby ledge. You will make it with three power. If playing in cooperative mode, go to the lowest point, kill your partner, then fall. With some practice and luck, your dead partner will re-spawn on another lower ledge. Now, walk as far to the right as possible and fall where some marines are standing. You should make it with one power. Have your partner kill himself and re-spawn down with you. There will now be no enemies during the rest of the level.

Hint: 343 Guilty Spark: Shortcut:
Tap X to get back in the Pelican. It will fly onto a ledge. Walk along the ledge in the direction you are going to end up above the tunnel where the Marines are fighting. Jump down to the tunnel, then continue the level.