At the screen where POD parts are purchased, press [Shift] + [F4] + 4 for an extra $1000. Note: This may only be done five times before each race.
Taunt opponent
Select tournament mode, highlight "Start Race" and press [Space] at the menu. Then an intermission that features your character and opponent taunting each other will appear. Note: This will not work if your character is the track favorite.
Bonus characters
Finish first place on the indicated track and circuit to unlock the corresponding racer: