Hidden car
Finish all ten missions in mission mode to unlock The Homer car. The car is selectable in any mode by choosing Homer's picture at the car select screen.
Hidden New Year's character
Set the system date to January 1 to unlock New Year's Krusty under the "?" at the character selection screen.
Hidden Halloween character
Set the system date to October 31 to unlock Halloween Bart (dressed in a Frankenstein costume) under the "?" at the character selection screen.
Hidden Thanksgiving character
Set the system date to November 22, 2001 to unlock Thanksgiving Marge (dressed in a Pilgrim costume) under the "?" at the character selection screen.
Hidden Christmas character
Set the system date to December 25 to unlock Christmas Apu (dressed in a Santa costume) under the "?" at the character selection screen.
Nighttime mode
At the options menu, hold L + R and press A(4). If you entered the code correctly, you will hear a sound.
Flat characters
At the options menu, hold L + R and press X(4) at the options menu. If you entered the code correctly, you will hear a sound. All the people (except the character you selected) will be flat.
Show collision lines
At the options menu, hold L + R and press B(2), A(2). If you entered the code correctly, you will hear a sound.
Hidden car
Finish all ten missions in mission mode to unlock The Homer car. The car is selectable in any mode by choosing Homer's picture at the car select screen.
Mission skip
Intentionally fail a mission five times to have the option to skip the mission. Note: This cannot be done on the final mission.
Extra time
To get +2 seconds, hit the phone booths that have Mr. Burns' picture on them. You can get +2 seconds in the road rage levels by running over the Transit bus stops.
Unlock expert mode
To unlock the special Expert Mode, press and hold L and R, then press START before you see the character selection screen. "Expert" will appear onscreen if done properly.
Unlock Soapbox Car
To unlock the Soapbox Car, go to the Options screen, press and hold R & L, then enter the following code: B, B, Y, X.
Unlock Smithers
To unlock Smithers, go to the Options screen, press and hold R & L, then enter the following code: B, B, Y, Y.
Unlock Nuclear Bus
To unlock the Nuclear Bus, go to the Options screen, press and hold R & L, then enter the following code: B, B, Y, A.
New Camera Views
To get more camera views, go to the Options screen, press and hold R & L, then enter the following code: B, B, B, B.
Unlock "The Car Built for Homer"
To Unlock the Car Built for Homer, beat all the 10 'Road Rage' levels.