So in the 1939 film The Wizard of Oz, in the scene where the Wicked Witch of the West disappears from Munchkinland in a puff of sulfurous smoke, Margaret Hamilton was supposed to stand on a trap door, which would take her below stage just as the pyrotechnics went off. Well, she went to her mark, the smoke went up, but the trap door didn’t open and she got a face full of flames (which was compounded by the copper-based green makeup she had on her face).
Almost seventy years later, during a production of the musical Wicked, at the end where Elphaba (the Wicked Witch of the West) is melted, the actress descends via a trap door and elevator, creating the illusion of being melted. Well, in one performance, Idina Menzel went to her mark, the trap door opened, but the elevator wasn’t ready for her, and she fell below stage and broke her leg.
The moral of this story: forget water and flying houses, trap doors are a witch’s kryptonite