When buying new parts for your Pod, press Shift+F4+4 to get an extra $1000 cash.
(This can only be done five times.)

Race as Sebulba

Successfully complete the Galactic Circuit to unlock Sebulba at the racer selection screen.

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.