"I wish I had a gag reel of every time I got whacked by that car door," Fox, 54, joked Sunday at the Back to the Future 30th anniversary cast reunion, held during London Comic Con. "[The reel] would be like 30 seconds of 'whack, whack!' "
Fox was joined onstage by nine other members of the franchise's cast, including Christopher Lloyd, who played slightly mad scientist "Doc" Emmett Brown; Claudia Wells, who played Marty's girlfriend, Jennifer; and Lea Thompson, who played Marty's mom, Lorraine.
Speaking animatedly throughout the fan event, Fox praised Lloyd as "a genius" to work with. Fox had praise for the audience, too.
Fox's Comic Con appearance is part of a schedule of events to aid his Up To 88 charity push, which hopes to raise $88,000 for The Michael J. Fox Foundation, benefiting Parkinson's research, before Back to the Future Day on Oct. 21.
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The number "88" has special significance for Fox and all Back to the Future fans, as it is the exact speed, in miles per hour, that the DeLorean had to reach before it could turn from a sports car into a time-traveling machine.
Similarly, Fox admitted to the crowd that he might not even be working as an actor now, if not for the movie's uplift on his career: It became the highest-grosser of 1985 and spawned two sequels.
(Though the franchise is less significant for Fox's kids, who "haven't watched it, not once," he said.)
"I was thinking of working on the fish dock or joining the military like my dad," he said. "Then suddenly I found myself on a set with Steven Spielberg."
Fox said he was "very overwhelmed by the whole experience."
"The nadir and the peak of my career happened at the same time," he said.
A special 30th anniversary Blu-ray, Back to the Future: The Complete Adventures, will be released on October 20 and will include all three movies, the complete animated series, a new bonus disc, a 64-page book and collectible light-up flux capacitor packaging.