Infinite lives:
Go to Training mode and find the letters F-L-I-K to gain an extra life. Repeat this over and over again to get as many as you want before returning to the regular game.

GameShark Codes
Infinite health        800A6594 0004
 
Infinite lives         800A65A0 3209
 
FLIK                   300A65A2 000F
 
Bonus training level

Finish all of Mr. Soil's objectives in the Training Mode. Bounce on all the spiders to kill them and reach a bonus level. Complete the bonus level to gain access and view three FMV sequences.