Nightmare Difficulty
How to unlock: Beat all the cups on Hard Mode with a gold trophy.

Black Bomb
You must eat a total of 5 ghosts with the Pac-Mobile in any of the cups.

Tracks

Easy Classic Cup	You must obtain a Gold Medal in Easy Watermelon Cup
Easy Rally Cup	You must obtain a Gold Medal in Easy Classic Cup
Easy Watermelon Cup	You must obtain a Gold Medal in Cherry Cup and Grapy Cup

Unlockable Characters
Pooka (from Dig-Dug) - Beat 'Rally Cup' on Normal Difficulty
The Prince(From Katamari Damacy) - Beat Rally Cup on Easy
Fygar - Beat Rally Cup on Hard Difficulty

Galaga Ship
How to unlock: Make sure to gobble-up at least 12 ghosts in the Classic Cup.

PS2 Cheats for Pac-Man World Rally

Pac-Man World Rally cheat codes

Pac-Man World Rally cheats