In order to find the Thing (F.F.) Character Token, you must open three hatches. Two of them are hidden in the main room - first on the left and second on the right side. Choose Iron Man to melt the golden one and blow up the silver one.
After pumping out water from the pond, choose any character with telekinesis power (e.g. Loki) and open the last hatch hidden near to the crocodile and pick up the Token.
Deadpool Red Brick
Choose Thor and jump down. Charge up the battery and wait for the metal cage with "Studs x8" Deadpool Brick. Now open it with Magneto and take the reward.
Stan Lee in Peril
On the last stage turn left as a character with claws (e.g. Wolverine), then dig out the elements of F.F. Panel from the sand pile. Put them together into one object and - as Mr. Fantastic - use it to rescue Stan Lee.