All art gallery:
Select the Tweety icon at the start game screen, then enter .RT as a code.
All mini-games:
Select the Daffy Duck icon at the start game screen, then enter ?BN as a code to unlock all the mini-games.
No whack in boxes:
Select the Taz icon at the start game screen, then enter WB as a code.
Two player Boss games:
Select the Big Red icon at the start game screen, then enter JC as a code.
Unlock Galleries:
Art Gallery 01 - Collect 10,000
Art Gallery 02 - Collect 30,000
Art Gallery 03 - Collect 60,000
Art Gallery 04 - Collect 110,000
Art Gallery 05 - Collect 185,000
Art Gallery 06 - Collect 285,000
Art Gallery 07 - Collect 535,000
Art Gallery 08 - Collect 1,035,000
Art Gallery 09 - Collect 1,785,000
Art Gallery 10 - Collect 2,785,000