Passwords:
When you open the Game, go to options and then go to Passwords. Change the letters in the boxes to enter the cheat. Enter the cheats below:

Code - Effect:
SLSDRDL - The game gets really hard
DSRDMRM - Turtles don't suffer any damage from things
MRLMRMR - Everything that increases your health Turns into pizzas
DRMSRLR - Your health recovers gradually

Unlock Bonus Fighters and Arcade Classic:
Unverified. Go to level 9-1 and locate a destroyed bus in one of the alleyways. You can jump onto the bus from some nearby boxes, and from the bus, you can reach the roof of a building.

Collect the 'antique item' and clear the stage with the item in hand. Go to the '2nd Time Around' menu and scroll through the objects of NY until you see an arcade marquee. Select the item, view the information and exit to get a system message.