Select the "Unlock Content" option at the "Extras" menu. Enter one of the following codes to unlock the corresponding bonus. Then, select the "Customize" option at the "Options" menu to activate the unlocked bonus.
Biker costume
Enter 1gb57M2x as a code.
Chef costume
Enter 51c24KiW as a code.
Gangster costume
Enter J5d99bPz as a code.
Kung Fu costume
Enter Ly11r98H as a code.
Mime costume
Enter 7qd33J1n as a code.
Velvet costume
Enter F9sT5v88 as a code.
Seventies costume
Enter S63bf2kd as a code.
Sixties costume
Enter M13Ni95L as a code.
Saucer attachments
Enter V81fvUW3 as a code.
Saucer skins
Enter X91mw7zp as a code.
Completion bonuses
Successfully complete the game to get almost 3,000,000 DNA and have ammunition recharge for your non-selected weapons.
Destroy All Humans! reference
Go to the Space Dust in Las Paradiso. Look closely at the movie posters to find an ad for the original Destroy All Humans!.
Halo reference
During the mission where you go in the Las Paridiso military base, Crypto says, "Maybe we should have brought the Master Chief along."
Mario, Sonic, and Halo series references
When you do the first story mission in Belleville, France, Pox will start to talk about video game ideas. Crypto will say, "You're a plumber, but you don't use plumbing stuff to kill your enemies, you just jump on them" (a reference to the Mario series), "You're a really fast hedgehog" (a reference to the Sonic series), and "You're a space marine on a planet with a ring around it" (a reference to the Halo series). Pox will say that all of the ideas suck or are crap and then makes up his own idea.
Monty Python And The Holy Grail reference
In Belleville, the S.W.A.T. and the army will often say ridiculous insults, such as "I fart in your general direction!" and "I wave my private parts at you, you son of a silly person!" These are direct references to the movie Monty Python And The Holy Grail, in which the protagonists are taunted by French guards with these exact quotes and many others.
Cheat Codes...