On the Loading Screen, press and hold A + X + Y + Z, and press Start to race in the dark.
Night Driving Off:
Perform the same code on the Loading Screen.
In Grand Prix Mode, enter the initials XYZ. This will enable all ten tracks in Arcade Mode, and turn on sixteen drones in Practice Mode.
Amazon Falls Hidden Path:
Pass the first hill, and slow down near the top of the second hill. Go through the road block to the right to find the hidden path.
Thanks to Revolution reader Jason Beeman!