Two improvements I'd like to see: 1) Faster movement 2) Baddies that don't float. The way it is now, it's hard to make out which square the enemy is standing on.
When I want to change players for a race I have to click Pause, click Quit to go back to the Main Menu, click Play, click the level set, click the race, click continue... too annoying. There should be a "change rider" button to take you directly to the selection screen.
Try the contest winner from Kongregate collabs! The url is http://cdn3.kongregate.com/assets/sound_files/0000/1146/Falling_from_Heaven__June_8__2009_.mp3
This game is really easy if you do the following: Use up ALL your time, and put in as many different moves as possible (more than you think you will use - you can then just cram the extra ones in the end). Then tweak the hell out of it.