Chapter Passwords
Enter the passwords at the Continue screen. Use the default input (all bugs) to skip the introduction sequence and start Chapter 1 immediately.
Password - Effect
Shell, Idol, Kid, Volcano, Eye, Nut, Volcano, Turtle - Chapter 2
Kid, Turtle, Volcano, Volcano, Turtle, Idol, Eye, Shell - Chapter 3
Bug, Turtle, Volcano, Volcano, Eye, Volcano, Kid, Shell - Chapter 4
Turtle, Volcano, Volcano, Volcano, Idol, Shell, Nut, Volcano - Chapter 5
Sound Test and Music
Switch on the console while holding A on Controller 2 to get the sound test menu.
If you switch on the console while holding B on Controller 2 you are treated to some music and background. The music loops forever (day/night).