1. While in two player mode on level "tanks alot" in the green base you can follow the sidepassage out side your base green can use this as a tank hiding area or as I do be tan and bomb the green base with out any troubles.

2. Press triangle and square at the same time on two player (this makes you run a little faster)

3. Pause the game and press R1,L1,hold R1 and press R2 then you have infinite weapons.

4. On the last level in the cementary there is a big statue in the middle. Blow it up with a motor and get explosives.