Clipping

Clipping is a glitch that is universal. It can happen in every video game. It happens a lot in Halo games though. Clipping is the glitch that allows you to get out of maps using Pan Cam.

Explanation
In a video game, the game has a certain frame rate. In most modern video games, the frame rate is between 30 and 100 frames per second. Halo 3's frame rate is locked at 30 FPS max. Halo 3's collision detection engine calculates at exactly that frame rate, so if an object is going slower than 30 frames per second towards an invisible wall, the object will hit the invisible wall; but if the object moves faster than 30 FPS, the collision detection engine won't see it collide with the other object. That is because the collision detection engine in Halo 3 does not have the ability to check where all objects are in-between frames. So example, the theater camera is moving at less than 30 FPS; the collision detection engine will stop it at an invisible wall. If the theater camera starts going more than 30 FPS, now the collision detection engine can't keep track of it in between frames, so the camera clipped through the invisible wall. Because, how the collision detection engine saw it, on one frame, the camera was on one side of the invisible wall, the next frame it was on the other side, so the game never saw the two collide, so the game didn't see the need to stop the camera. That is how Pan Cam can glitch you out of a map.