Level select
Hold [L] and quickly press [Z], [C-Up],
[C-Down] at the level selection screen to unlock all levels.
Mirror levels
Successfully complete levels 1 through 4. A message
will appear after the credits will confirm correct trick entry.
Press [Z] when selecting a level in time attack, two player,
and championship modes to play on the mirrored version.
Bonus characters
Successfully complete the mirror levels 1 through 4
with Skier and Boarder. A message confirming that the three bonus
characters (robot, bear, disco dancer) have been unlocked will
appear after the credits.