Enter one of the passwords at the "Secrets" menu:

Code - Effect

EGOPROBLEM - Big heads
HUDBEGONE - Disable HUD
THISISTOOHARD - Easier game
FROZPROF - Frozone gets 1,000 experience points
FROZMASTER - Frozone has everything at max
FROZBOOM - Frozone's Super move
SHOWME - Full gallery unlocked
THISISTOOEASY - Harder game
LEVELLOCKSMITH - Level select
INAHURRY - Mr. Incredible and Frozone move faster
MRIPROF - Mr. Incredible gets 1,000 experience points
MRIMASTER - Mr. Incredible has everything at max
MRIBOOM - Mr. Incredible's Super move
HEADROOM - Small heads
WHYMUSTWEFIGHT - Unlimited energy
ROLLCALL - View credits