MAC gun glitch

Description
On the Return to Sender part of the Cairo Station in Halo 2 campaign, there is a metal object moving back and forth. When it moves back, a MAC shell is loaded into it, and when it moves forward it loads the shell into what might be the MAC gun itself. If you get in the way of the "metal object" when it comes forward, you will be killed, but you will drop through a hole and see the room the Master Chief is in when he returns the bomb to the Covenant in the cutscene.

Also, you can get stuck in the MAC gun barrel and get shot out into space. Just stand in front of the reloading "metal object" and wait for it to push you into the barrel. You will die and get shot out into space, just like a MAC round. Elites can also get stuck in it, which makes it difficult, if not impossible, to finish the level.