Headlong Vacation

The Headlong Vacation is a glitch that can be done on the multiplayer map, Headlong in Halo 2 that allows players to bypass invisible walls. There may be more ways to do this, but this is the way I found.

Banshee Method
This can be done single player or Co-op. If you do it single player, follow these steps: Note: If you use this method, the Banshee can't go any higher than gliding along the floor because of an invisible wall.
 * Grab the Banshee
 * Fly over towards the water
 * Look to your left and you should see a slanted wall
 * Fly your Banshee over to the wall, WITHOUT using boost, and then, at an angle, slowly fly the Banshee up the wall and you should bypass the invisible wall.
 * You are now free to walk around this area outside the map

If you do it in Co-op, follow these steps:
 * Acquire the Banshee, and have one player stand on your Banshee
 * Fly over towards the wall
 * Same as before, except just fly straight up the wall
 * Once the Banshee reaches the invisible wall, have the player move to the tip of one of the Banshee's wings, and have them jump off
 * If performed correctly, they should jump right past the invisible wall