DS Wario Stadium - So Wario has adorned this place with statues of himself, the vain little...At the end of the track, use a Mushroom to cut through mud on the last turn.
GCN Sherbet Land - There are a lot of areas filled with difficult to move through snow and you can use Mushrooms to get past these areas, cutting off corners. In the area with all the Freezies, drive your kart to the left of the tall ice block structure. Use the Mushroom to reach a secret Gliding area!
3DS Music Park - There's a bit of a trick to get the second one right! After you pass the two Piranha Plants, use a Mushroom to get onto the ramp on the left. In this section, listen carefully to the music when approaching the giant bouncing Music Notes, if you time a hop correctly and in rhythm after the third tick (tic-tic-tic-jump), the music note jumps and you will get a speed boost. This works for both music notes. On the final lap, the tempo is faster and it will be more difficult to time your hop and get the boost.
Under the second giant bouncing Music Note is a patch of grass. Use a Mushroom to quickly speed through this area.
N64 Yoshi Valley - This place has a serious amount of choices laid out before you! The fastest route should be the small bridge immediately to your left when you enter the maze! After you pass the giant egg and the bridge, use a Mushroom to jump off the ramp on the right and if you pass the ramp, use a Mushroom to cut through the entire final turn!