Secret Room on The Ark

The Secret Room on The Ark is a glitch on Halo 3's Campaign level The Ark. It is used in the cutscenes in the beginning and end of the level.

Tutorial
To get into the room, start up the level from the beginning. Once you land on the ground and get out of the Pelican, you can end the game. Now, go to theater and start the film. Go to the part where you're just about to get out of the Pelican. Start watching in slow motion from there. Keep going in slow-mo until the words "Installation 00" are nearly gone but the black bars are still there. Next, detach the theater camera. Back it up. Now look up and you should see a little ledge like area on the rocks. Go up there. Get against the wall and quickly press "Y" twice. If done right, you should glitch inside the purple room.

Explanation
This room technically isn't a glitch, and technically isn't an easter egg either. The method used to get into the room however is a glitch. The reason for this room's existence has to do with how cutscenes are made in the Halo games. They aren't pre-made and then inserted into the level. They're rendered using game resources, meaning that the location of the cutscene has to be somewhere in the level. That's why throwing a grenade right before a cutscene leaves a burn mark.

Other Stuff

 * This room also appears on the level Floodgate, but that one can't be seen without the help of Pan-Cam.
 * This room is the room where the Tilt skull is on the mission Cortana, except without all of the Flood mass.
 * The doors in the room are blue, meaning that if a player could get near them in the game, they would open.