Nice try message:
Press Up(2), Down(2), Left, Right, Left, Right, B, A when "Press Start" appears at the title screen.

Super speed:
Hold Up + A during game play in any level and you will go much faster.

Master code:
Press Down(2), Up(2), Left, Right, Left, Right, B, A when "Press Start" appears at the title screen. All bonuses and practice levels will be unlocked.

Blocky graphics:
Press Left(2), Right(2), Down(2), A when "Press Start" appears at the title screen. The game title will change to confirm correct code entry. The game's frame rate will improve, at the expense of graphics quality.

Beginner level 2: Warp To level 5:
Instead of going forwards towards the goal, turn around and go up the little point. Fall off and land on a platform beneath. There should be another goal there that warps you to level 5.