Though the end result is effortlessly entertaining, making Back to Future (1985) was as difficult as generating 1.21 gigawatts of power. The filmmakers dealt with story changes, scheduling troubles, and one of the most notorious recastings in Hollywood history. And as is the case with most movie productions, there were plenty of goofs that didn't make the final cut.
The blooper reel for Back to Future shows the cast messing up and cracking up on set. Though their characters conquered time travel, the film's leads struggled with opening doors and windows when the cameras were rolling. Michael J. Fox, who plays Marty McFly, was especially mistake-prone judging by the footage. Hopping between the sets of Family Ties to Back to the Future on just a few hours of sleep probably didn't help with Fox's coordination.
Some unused footage from the sci-fi comedy is nearly as fascinating as the actual film. Before Fox officially signed on to play Marty, Eric Stoltz spent a month shooting principal photography for the role. A few snippets of Stolz's performance before he was recast are available online.
You can view the full gag reel from the first Back to the Future movie below. Here are more facts about the franchise.