ATR

Bonus tracks (two player mode):
Begin game play in single player mode and reach the bonus tracks.
Intentionally lose and enter ATR as a name on the high score screen.
Restart the game and select two player battle mode to access any bonus track.

Space World:
Select battle mode and choose Forest World.
Select track two and race in a formula car.
Intentionally allow player one win all the races.
Select battle mode after returning to the title screen.
Space World will now be selectable.