Become Invisible:
To make yourself invisible, pause the game and press these buttons: LEFT, RIGHT, LEFT, RIGHT, Z, Z, R.

Coin Locations:
To unlock North America in Joy Ride mode, earn all the following coins:

Russia - On an island in the corner of the level. Beware that if you go too far on the side that's not closest to land, you'll get stuck.

Vietnam - On the side of the volcano. The volcano is on the east side of the map.

Russian Winter - Go to the burned village. The coin will be in a crater in the corner of the village area.

Eastern Europe - In the Industial City drive up one of the ramps built into a building. Jump the ramps for the coin in mid-air.
Submitted by - Spike & BO
Infinite Countermeasures
One of the most helpful codes for all you token hunters struggling with the Joy Ride mode, this button cheat gets you infinite countermeasures. Just press pause and enter Y, Y, Y, X, X, Z, Z and you're ready to kick butt.

Turn Off Gravity:
To turn off gravity, pause the game and press X, Z, X, Z, UP, UP, UP. Every time you hit another vehicle, it will float.

Unlock Hover Sled:
To get your hands on the GameCube-exclusive Hover Sled, finish each Smuggler's mission with a GREAT rating.