The game's passwords are all references to Clint Eastwood projects. CLYDE (Infinite lives) is the name of the orangutan in "Every Which Way But Loose". MISTY (Level 2) is a reference to "Play Misty For Me". BIRD (Level 3) is a reference to the Jazz biopic "Bird". "GUNNY" (the password does nothing) is a reference to a character in "Heartbreak Ridge".