Destroyed vehicles glitch
From Halopedia, the Halo wiki
The Getting Inside Destroyed Vehicles glitch only works on Halo 3.
Tutorial
To do the Get Inside Destroyed Vehicles Glitch, you will need a Spartan Laser. First, approach a vehicle (preferably a Banshee) and stand next to it (your body must be touching the vehicle). Press RT (Right Trigger), then RB to enter/ride/drive on top. Next, charge the Spartan Laser and just as you fire, enter the vehicle. Note: you cannot drive the vehicle.
Another way to get inside a destroyed vehicle is to have someone damage the vehicle with a Fragmentation Grenade or two until it is at the point in which it will blow up if you stick someone with a Plasma Grenade who gets in it. First, get your friend to stand next to a vehicle. Next, have them get in, stick them and board their vehicle. If done right, the vehicle should be damaged or destroyed and you should be able to ride it. But make sure you do this fast, or it WILL NOT work. Two players, an Overshield, and a Missile Pod will work just as well. The first thing to do is that the first player stand next to a vehicle with an Overshield, and have the second player with a Missile Pod fire at the vehicle while the first player gets in. If timed right you will be in the driver's seat.
Note
This has been confirmed to work with the Banshee, Hornet, Brute Chopper and Ghost. You will eventually respawn due to wreckage automatically being removed from the map after a certain amount of time. It should also be noted that many have destroyed a Banshee on the river in Valhalla and that the person inside will float downstream, creating a raft-like experience. Also, this glitch works on all vehicles that you board, force out the driver, and take their place (Brute Chopper, Hornet, Ghost, Banshee), and the Warthog's gunner seat whilst destroyed. The glitch should work on all maps, since maps themselves do not play a part on whether the glitch will work or not; some just happen not to have certain vehicles.
As with the raft-like experience with the destroyed banshee, if the "raft" is turned upside down, the person will not be ejected. While this is only confirmed with the banshee, it probably does work with others as well.
