Extra money:
Press [Shift] + [F4] + 4 at the screen where POD parts are purchased. Note: This can only be used five times after completing each race, regardless of outcome. Press [Ctrl] + [F4] + 4 for even more money.

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. 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.

Press [F6] during a race to yell and call your opponents names.

Mirrored racks:
Get a first place finish in each of the 24 tracks in championship mode.

Bonus characters:
Finish first in the indicated track and circuit to unlock the corresponding racer.

Racer - Track/Circuit:

Aldar Beedo - Beedo's Wild Ride/Amateur
Ark Bumpy Roose - Bumpy's Breakers/Semi-pro
Ben Quadinaros - Inferno/Invitational
Boles Roor - Zugga Challenge/Semi-pro
Bozzie Baranta - Abyss/Invitational
Bullseye Navior - Sunken City/Semi-pro
Clegg Holdfast - Aquilaris Classic/Amateur
Fud Sang - Vengeance/Amateur
Mars Guo - Spice Mine Run/Amateur
Mawhonic - Andobi Mountain Run/Galactic
Neva Kee - Baroo Coast/Semi-pro
Ratts Tyerell - Howler Gorge/Semi-pro
Sebulba - Boonta Classic/Galactic
Slide Paramita - AP Centrum/Invitational
Teemto Pagalies - Mon Gazza Speedway/Amateur
Toy Dampner - Executioner/Galactic
Wan Sandage - Scrapper's Run/Semi-pro