Short-lived live event (April 2003) on the lower lot featuring characters from the Marvel Universe. Timed to coincide with the release of Ang Lee's Hulk, and showcasing some props and set pieces from that movie.
The story is set in the X-Men Training Academy, and it's time to find a mutant loose somewhere on the Lower Lot. A couple of family members from the audience are invited onto stage to determine if they are mutants. As soon as the child sits in the mutant chair, the bookshelves collapse on the back of the set, 'proving' the child has mental powers. Magneto appears above the stage (on a large Panasonic videowall). The rest of the Marvel characters appear in cars and on quad bikes, and Daredevil leaps off the adjacent soundstage (the E.T. Adventure show building, at the time) to join them.

Thanks to Phillip Donnelly for the photos and description.