Big Head Mode: 
Type "big heads" at the main menu. 

Super Air:
Go to the end of a map where there is a big hill that goes straight up. Go a fair distance back
and race full speed towards the hill. You should be able to make it up the hill. Once you're up,
keep going forward and eventually you will be blown really high up in the sky. This can be
done on any track except the Supercross tracks.

Quick Recovery:
If you fall off your bike, press Tab to get back on.

Rainbow Studios:
During the game , press Alt + Tab + A and it will change screens. Go back to the game to see
the Rainbow Studios' pattern. When your sick of this look , remove it by simply restarting the
race.