During the Deja Vu mission, you can unlock two different skins for use in the Deja Vu mission.

Skin	How to unlock
Classic Gray Fox skin	Reenact all scenes, on hard, and correctly answer all quiz questions after the credits.
Classic Snake skin	Reenact all scenes, on normal, and correctly answer all of the quiz questions after the credits.
Raiden re-skin (White)	Complete Jemais Vu mission on Normal difficulty.
Raiden re-skin (Green)	Complete Jemais Vu mission on Hard difficulty.