Unlockables - Successfully complete the indicated goal on the "Goal Board" menu to unlock the corresponding bonus:

Around The World: Clear all six courses. Difficulties do not have to match. This unlocks Marathon mode.
Battle Fan: Play 10 games of either Battle mode. This unlocks six more Battle levels.
Cleared A Course: Successfully complete one course on any difficulty. This unlocks Course 4.
Extra! Extra!: Reach any Extra stage. This unlocks "Indulgence" in the Music Player.
Fanatic: Raise the Total Clear Rate to at least 90% in either Single Player or Co-op mode. This unlocks "Kitty Cat" in the Music Player.
Floor It: Successfully complete any course using Turbo Speed. This unlocks the Extreme Speed setting.
Got Three: Successfully complete three different courses on any difficulty. This unlocks Course 6.
I'm a Survivor: Last for 4 minutes on any level in Survival mode. This unlocks six more Survival levels.
More Please: Collect a grand total of 250 targets. This unlocks the Turbo Speed setting.
Step Up: Successfully complete any course on the Difficult difficulty. This unlocks the Expert difficulty.
Two Down: Successfully complete two different courses on any difficulty. This unlocks Course 5.
Uh-oh...: Successfully complete all six courses on the Expert difficulty. This unlocks the Master difficulty.

Control replay - Successfully complete a level to see a brief replay of that level. Press X during the replay to repeat that short segment or Y to see the entire replay of that level.