Charles Austin Miller

Continuity mistake: After George knocks out Biff, Biff has an obvious contusion and blood on the right side of his nose and mouth. As the hoverboard chase scene progresses over the next several minutes (particularly in the lighted tunnel), the contusion and blood repeatedly disappear and reappear on Biff's face from one camera cut to the next.

Charles Austin Miller

Trivia: According to Robert Zemeckis, the kitchen scene with Michael J. Fox playing three characters simultaneously (middle-aged Marty McFly, his goofy son and bubble-headed daughter all sitting at the same table) was a nightmare to shoot. The characters required individual matte shots that were later spliced together into one scene, requiring many takes; so every visible object in the kitchen background had to remain perfectly stationary and consistent over several days of filming. Thinking ahead, Zemeckis ordered his property crew to hot-glue every single background object in the kitchen in-place, to prevent accidental movement. However, when they were well into filming the tricky scene, the studio was struck by an earthquake, which essentially destroyed the kitchen set, hot glue and all, requiring a rebuild and complete re-shoot.

Charles Austin Miller