Double Trouble
If you hold down the L1, Triangle and X button, whilst pressing up on the joypad, as the game loads, you should get two ships during the Galaga game , rather than one. Side by side, these give you twice as much firepower and twice as much chance of completing the game and accessing the bonus cars.
Extra Tracks
Finish all four tracks in the first place to gain access to another four. These are essentially the same four as before, except they are raced backwards! This may sound easy, but believe me its not.
Flag Tricks
Whenever you start a race, you will see a chequered flag waving in the wind. If you hold down the L1, L2, R1 and R2 buttons and press the D-pad you can make it flip and rotate in different directions. Alternatively, you can press the X button to zoom in on it and the Square button to zoom away from it. Pressing start as well, will also make the flag go transparent. Remember though, the L1, L2, R1 and R2 buttons have to be held down throughout for these tricks to work.