Enter these passwords on the password screen:

Password - Effect

543961 - 1 Level Down
574439 - End
178931 - Linc Hideout
692730 - Security Building
280870 - Subway
000000 - The Beginning
623845 - The Factory
936842 - The Furnace
986254 - With Eduardo
180283 - With Mrs. Piermont
810354 - With Potts