Could someone tell me where to find those so I know where to look during my next playthrough.
Also, I heard you could find Ra's al Ghul's body/cell in the game. Where is that?
Forgot about that one. Ra's is near Dr. Young's office. There's an open cabinet with cadaver sticking out. Ra's Al Ghul is on the toe tag.
Here are the ones I remember. I believe I remembered them correctly.
Mr. Freeze's cell- In the area where Harley is defeated. It's on the right when you enter. You can't miss it.
Scarface's tommy gun(On Display)- In the area where Harley turns on the floor zappers. Go up to where you fight the thugs, there's a platform you can walk across to like a guardroom. The gun is on the wall.
Alice in Wonderland tea set- Botanical Gardens, 2nd level under the door across from the entrance
Clayface- In a cell where you find the Warden.
Catwoman's mask/claws(On Display)- Arkham Mansion, the hallway before you enter the Warden's Office
Zsasz' body art with guards- There are two I believe. One is in the Botanical Gardens on the left shortly after you enter. Another is up in a guard room by the penitentiary
Bane's teddy bear- It's in a room you enter before you stop Harley from killing Gordon and fight Bane.
Ratcatcher's gear- I forget what building but it's below a grate in a duct. I think it's in the Botanical Gardens but am not sure.