Scooby-Doo: Mystery Mayhem Cheats - PlayStation 2

card
When you need the access card so that Scooby and Shaggy can get through the mist. You must first three mists then go to one of the lockers. One should open and have the red access card inside. Then, go over to the controls so that you can get the robot. Take it over to the red access card door. The door should then open. Go in and turn off all of the knobs. You are now able to go through the door that was blocked by steam.

Weird Wild West: Busting Freddy out of jail
On the other side of main street from the jail where you have to bust Fred out, there will be a small alleyway. Have Scooby crawl underneath the fence to find the liquid soap, then go back to the side of the jail where the hole is blocked by the cart full of gold. Use the liquid soap, and it will slip right over.

Weird Wild West: Safe code
The safe which is in the bank has a three digit code. The code is "1-3-7". It can be found written on the blackboard in the schoolhouse.

Opening the bridge
On level 2, to open the bridge there are four switches. Press switches 1, 2, and 4.

Mini-games
Get the five hidden sandwich ingredients in a level to unlock a mini-game.

Trap The Fake Ghost mini-game mini-game: Collect the ingredients in level 1.
Monster Frenzy mini-game: Collect the ingredients in level 2.
Mine Cart mini-game: Collect the ingredients in level 3.
Trail Bike mini-game mini-game: Collect the ingredients in level 4.
Spooky Science mini-game: Collect the ingredients in level 5.