Gauntlet Level 1: Level warps
Use the exit in the bottom right corner to warp to level 4. Use the exit in the top 
right corner to warp to level 8.

Gauntlet Level 4: Level warps
Use the hidden exit to the right of the main exit to warp to level 8.

Rampage Alternate character
Select a single player game. Use controller two to play as Lizzie.

Roadblasters Level warp
Enable the Indestructible Demo Mode option then complete the first ten levels. 
When you start level 11 you will warp to level 50.