Hidden tracks and vehicles:
Win all gold medals in the world tour divisions to unlock extra tracks in world tour and arcade modes as well as extra vehicles in arcade mode.

Master code:
Enter ZAKARY X as a name to activate all codes in the game.

Stunt mode:
Enter TURN TRICKS as a name to be able to turn while in mid-air.

Sumo mode:
Enter YOKOZUNA as a name to increase collision effects.

All divisions:
Enter SAD CLOWN as a name.

All tracks:
Enter LEAD TO ROME as a name.

All upgrades:
Enter MAD HOOKUP as a name.

Hint: New York shortcut:
There is a movie theater in the New York track where you can ram the front glass. Travel straight through it and come out the other side.