From Halopedia, the Halo wiki
The Requiem vacation is a glitch that can be performed on the Halo 4 campaign level Requiem which allows the player to break the boundries of the playable area and explore the map at will. It requires a Banshee.
- Begin the level at Rally Point Bravo.
- Proceede to the area with the bridge. At the opposite end there is a banshee.
- Enter the banshee. Fly it to a safe area and meele the wings off.
- On the opposite end of the bridge there is a small opening in the rocks below the main opening. Fly the banshee through this. It will fit without its wings.
- You are now out of the map, and may explore.