Fox fell as he joined co-stars Christopher Lloyd, 84, who played Back to the Future co-lead Doctor Emmett Brown and Tom Wilson, 64, who played antagonist Biff Tannen, at a Fan Expo event when he tumbled.
The 61-year-old appeared to catch his foot and fall when walking to the sofa on-stage.
Fox fortunately landed on the soft couch.
The father-of-four recovered quickly and used some good humour to carry on with the discussion.