In several of the races, there are areas the player can head for that the computer normally does not. These are shortcuts.

Here's a few tips on how to find these:

1. If you see a yellow band (i.e. a yellow strip that makes your kart jump) in an odd place, it may be a shortcut.
2. Look closely at the map. Some tracks have narrow ledges that can allow you to skip 180 degree turns.
3. Remember: the more boost tiles (the flashing red and yellow arrows on the track) that you hit in sequence, the higher you'll fly if you hit a yellow band.

To date, I've found shortcuts in the following courses:

Boo Lake
Sky Garden
2 in Snow Land
Rainbow Road