Erm...the game doesn't go to fullscreen all that well in my machine and was somewhat slow to switch back. It wouldn't fit (I have a square-ish monitor).
Also, if you reverse and go forward at the finishing line, you get one hell of an amazing lap time. One way you could prevent this is forcing the player to complete a few invisible checkpoints.
I would also reverse the arrows. My mind glitched badly on this =P I was in fact trying to go around the finishing lane thru the grass but simply gave up.
Don't feel discouraged - this could become a very fun racer, in the style of Micro Machines =)