Bonus vehicles
At the car selection screen, hold C-Up + C-Left + C-Down. Now the Muscle Car will become an All Terrain Vehicle, the La Bomba will become a School Bus, and the Devastator will become a Police Car.

Golden Gate Park track
At the track selection screen, hold L + C-Left + C-Down. Now the U.S. 101 track will become Golden Gate Park.

San Francisco track
At the track selection screen, hold L + C-Right + C-Down. Now the Grand Canyon track will become San Francisco.

Indiana track
At the track selection screen, hold L + C-Right + C-Up. Now the Beverly Hills track will become Indiana.