Xbox
 
 
 During a mission, pause the game, choose "In Game Options" then select "Enter Cheats" and input one or several of the following button combos:
B, B, X, A Superman (Player Invincibility)
B, B, X, B Team Superman (Team Invinvibility)
B, B, X, X Full Ammo
B, B, X, Y Finish Current Mission

Thanks to Revolution reader Q!