Moon Gravity
At the main menu screen, press Up, Up, Up, Up, R1, Square, Circle. There will be a quick flash indicator in the bottom left-hand corner of the screen if you enter the code correctly. This will allow you to float through the air after each jump, so that you may do endless combinations of multiple tricks to rack up points.
Unlimited Turbo Boost
At the main menu screen, press R2, L1, Square, Circle, Circle, Circle. There will be a quick flash indicator in the bottom left-hand corner of the screen if you enter the code correctly. You will be allowed to use unlimited Nitros in any race.