Re-Volt

Invert track:
Press R + L+ Down at the track selection screen.

All cars:
Enter CARTOON as a name. Note: Enter CARNIVAL as a name in the European version.
Information in this section was contributed by Shahin and Jim S, and Falcon.

All tracks:
Enter TRACTION as a name. Note: Enter TRACKER as a name in the European version.
Information in this section was contributed by Shahin and Jim S, and Falcon.

All weapons:
Enter YOY or OYOY as a name. Press L + R to change weapons. Note: Enter SADIST as a name in the European version.
Information in this section was contributed by Shahin, Jim S, and Falcon.

Tiny mode:
Enter MAGGOT as a name.
Information in this section was contributed by Jim S and Falcon.

Change cars:
Enter CHANCER or CHANGER as a name.
Information in this section was contributed by Jim S and Falcon.

Enable UFO:
Enter YUEFO as a name.
Information in this section was contributed by Jim S and Falcon.

Hi-Fi mode:
Enter FLYBOY as a name to increase the car details..
Information in this section was contributed by Jim S and Falcon.

Edit progress table:
Enter GOATY as a name.
Information in this section was contributed by Jim S and Falcon.

Clockwork Carnage mode:
Collect all of the stars in the stunt track.
Information in this section was contributed by ElPikaloco.

Extra cars:
Enable the "All cars" and "Enable UFO" codes. At the car selection menu, go to where the Probe UFO is located. There will be a Trolley (which may not have wheels sometimes), Clockwork Wun, Clockwork Too, Clockwork Tree, Clockwork, and Mystery car. Note: These cars will be disabled when the Dreamcast is powered off.
Information in this section was contributed by g_man1.

Flying cars:
Enter the "Enable UFO" code, then the "Change cars" code. Select the UFO as a vehicle, then use the D-pad to change to a car when game play begins. Your car will be flying like the UFO. Note: The reverse is also true. This trick actually allows you to use the physics and "win screen" of the car you selected. For example, if you select the RG1 as a car, then use the Probe UFO, you will fall like a rock (with the RG1 physics).
Information in this section was contributed by Tipay.

Strange cars:
Unlock Clockwork Carnage Mode, then select it. Enable the "Change cars" code. Select any track and while racing, press Up or Down. You should change into a different car. The car will be black or white or some other color (RC San should be a pixellated blue) and may have point-ended wheels (Big Volt is a good example).
Information in this section was contributed by iftnfs.