Shielded dead Elite
From Halopedia, the Halo wiki
Template:Ratings To see a "Dead Shielded Elite", you must play Halo: Combat Evolved, where there is a glitch that allows you to see an Elite's shield, even when it is deceased.
To do this, start any level and play through it on any difficulty, until you reach an Elite, any variant will do. Do not attack him, instead, wait until you get behind him or sneak up on him, then beat him in the back, so that he'll instantly die. Now that you've done that, shoot his corpse. It should flicker like the Elites shield isn't disabled. This works with all types of Elites, even Zealots. However, it doesn't work in Halo 2. But it does occur in Halo 3 through means of bad connection or filtering errors that cause coding errors.
The easiest way to see this glitch is to start Assault on the Control Room, and play until you get to the bridge. There is an Elite on the lower level (usually a Major Domo). Simply catch him off guard and hit him in the back and shoot his corpse to see the glitch.