Light Eye
From Halopedia, the Halo wiki
The Light Eye is a glitch on Halo 2 on any level. The glitch can make the lights on Warthog show through the walls as if the walls were foggy windows.
Walkthrough
This glitch is like most glitches in the it is very difficult to get it to happen but when it does it is very plain to see. To perform this glitch you must start any level, and find a point where an Elite, Grunt, or a Warthog with passengers. Go behind a wall on their own accord. When this happens, you must save and quit and then restart the game from where you were. Now you must look at the chosen Covenant or Warthog and the lights on them should show right through the walls.