All tune ups
At the title screen, hold L + B and press Up.
Extra modes
At the title screen, hold L + B and press Down.
All cars
At the title screen, hold L + B and press Left.
All tracks
At the title screen, hold L + B and press Right.
Super Mario Circuit 1 (from Super Mario Kart)
Select the Hornet track in Quick race or time trial mode and enjoy driving!
Note: The Hornet Track is the exact layout as the Super Mario Circuit 1 track except that it is set in a different scenery.