Secret warps

Level 1 to level 4
- Get flowerpot and press '1' followed by F7

Level 2 to level 22
- Kill all monsters and jump onto rolling hoop and then press '3' followed by F7

Level 3 to level 15
- Get trophy and press '4' followed by F7

Level 5 to level 8
- Get teapot and press '8' followed by F7

Level 10 to level 14
- Get pitchfork and press '4' followed by '5' followed by F7

Level 16 to level 19
- Get pie and tube 1 then press '9' followed by F7

Cheat Mode

Enter specialcode '57502' on the options screen and press 'A'+F3. This will enable the following keys.
F - Float
Q - Next Level
A - Previous Level
Z - Resets timer and player position

Press any two number keys to skip to the corresponding level.
Example: Press '0' followed by '7' to skip to level 7. Press '2' followed by '3' to skip to level 23