The Wizard of Oz – A Serious Mistake
No unplanned moment on this list is more unfortunate than this one. On the set of The Wizard of Oz, actress Margaret Hamilton (who played the Wicked Witch of the West) was accidentally burned by a stunt fire that was set off too soon. She had to be rushed to the hospital. Because she needed time to heal and could not reshoot the scene, the filmmakers were forced to include the faulty take in the film.