While in game play type the following cheats and hit enter. 

TREX -Instead of racing in a monster truck you can race in a large car eating dinosaur. Hit CTRL-3 to see a great chase-plane view of it. 
FRAME - Show frame rate 
DANCE - Strange wiggley graphics 

Emergency Airlift: 
If you're ever stuck in a ditch and you are on all four wheels, 
press H and either a helicopter or a prehistoric bird lifts you up. 

Lighning Speed in Arizona:
At the first screen select professional. On the second 
screen choose Rally and on the third screen choose Arizona. 
While racing you'll come upon a train. Go over on its tracks 
facing away from the train. Hold forward and press Ctrl. 
You'll go over 100 MPH! 

Mud Pies Shortcut: 
After the second checkpoint in Mud Pies, you will come to 
the turn which crosses the concrete bridge which goes over 
the lake. Go straight and there will be a sign missing of the three 
turn signs. Hit the ramp and fly over the lake. Go straight and 
you'll hit the course again, gaining at least five seconds on 
your opponents. 

Round and Round Shortcut: 
Instead of going through the red covered bridge you can jump 
over the lake. Before you make the turn to go on the bridge you 
go straight and you will jump over the lake landing on the other 
side. It saves you from getting stuck in the water. 

Shortcuts: 
In Arizona, when you first enter the city turn right and follow 
the road until you get to checkpoint 6.

When on the Yucatan Adventure rally, you will cross the first 
bridge over the ocean. After you cross it, you will see a volcano. 
Go up the volcano, following the strips of road along the way. 
It will lead you to the second bridge, with a much quicker time.

In Highlands Rally, after passing checkpoint #5, follow the road 
untill you see road blocks, this being where the road turns at a 
90 degree angle. Follow the little road, go up the mountain for 
some major air-time, and you will land on a bridge. Race to the 
finish line. 

Soccer Field: 
Start a rally race and choose Highlands Rally. Instead of going 
straight, turn left. There will be a road that points off into a valley. 
In that valley, there is a soccerball and two goal posts on each 
end of the field. 

Torture Pit (hidden track): 
While Racing on Sidewinder Canyon race to the 4th 
checkpoint. Go past the bridge and make a quick right going 
through the barricades to the right. Follow the dirt path and 
stop after the first bridge and make a right onto another bridge 
and follow that bridge to the end and you will see a checkpoint 
that will say "pit" go throught the checkpoint and follow the 
on screen instructions and you'll get the track.