To unlock the following riders, go to the Press Start screen and enter the corresponding codes quickly:
Day Smith: TRIANGLE, UP, DOWN, UP, DOWN, SQUARE
Vanessa: TRIANGLE, DOWN, LEFT, LEFT, DOWN, SQUARE
Big Foot: TRIANGLE, RIGHT, UP, RIGHT, UP, SQUARE
The Mime: TRIANGLE, LEFT, RIGHT, LEFT, RIGHT, LEFT
Volcano: TRIANGLE, UP, UP, X, UP, UP, X