Alternate characters
Select a single player game. Use controller two to play as Lizzie or controller three to play as Ralph.
Gauntlet-Level Skip
There are 3 hidden level warps between Levels 1 & 4. In Level 1, an exit in the lower-right corner of the map will send you to Level 4. An exit in the upper-right corner will send you to Level 8. In Level 4, there is another hidden exit to the right of the main exit that will also send you to Level 8.
Vindicators-skip levels
Upon completing certain stations (including stations 4 & 6), you have the option to skip the next station. It is an available option on the "Customize Your Tank" menu-it costs 2 stars to skip the station.