Rtas 'Vadum's eyes glitch
From Halopedia, the Halo wiki
The Half Jaw's Eyes Glitch only appears in the level The Oracle, right after the level The Arbiter ends.
You can only see this at the part where you just start the level. Wait until Half Jaw and the other SpecOps Elites turn invisible, then look at Half Jaw's eyes. Although he's invisible, his eyes are still green and stand out from his Active Camo. This does not affect him in any way and doesn't occur with any other Elites.
It cannot be seen in Halo 3 as Half Jaw can only be seen in cinematics and not in actual gameplay.
