Level select:
Hold L + Z + C-Up + C-Down at the title screen for approximately five seconds. 
The sound of a bang will confirm correct code entry and the character 
selection screen will appear. An entry for the "Car Park" level will be 
displayed at the top center of the screen. Press C-Left or C-Right to select 
a new starting level. Note: This also enables invincibility to most attacks. 
Explosions and special moves will still cause damage. Also, bazookas get 30 
rounds of ammunitions and flare guns get 10 rounds. 

Hidden weapons:
The following objects can also be used as weapons. 

Totally destroy a car, then Smasher can pick up the engine and use it as a 
weapon. 

Destroy the airplane at the Airbase to use its gun. 

Destroy the two large black structures found in the Hovercraft level to get 
a flare gun. 

Destroy the police car in the Car Park level to get a rocket launcher. 

Go to your left as soon as you enter the reception level and destroy the 
farthest box to get a pistol and 2 grenades. 

After entering the Bronx level, keep going straight and pass the train that 
throws bombs at your character. Then, turn left and break open the brown 
gate to get a pistol in each of the two left boxes in the gate. 

Destroy the first car on the bridge level to get a pistol. Destroy the 
second car at the end to get a shotgun. 

Destroy the parked black car inside the gate in the Car Park level to get 
a shotgun. 

More money:
Repeatedly roll against a wall until money appears. 

When you find a wall, run and press A or B to receive money.

Restore health:
Keep hitting the soda machines. Drink the cans that appear from them to 
restore a small amount of health.

Levitating character:
Play the Truck Driver level in two player mode. Allow the trucker to grab 
one of the players. Have the other player knock the trucker down as he is 
just about to toss the first player. The player that was grabbed will 
remain in mid-air for the remainder of the game.