1. There was never supposed to be a sequel. Contrary to popular belief, Robert Zemeckis and Steven Spielberg had never intended for the original movie to have a sequel. “But what about the flying car at the end?” That was merely supposed to be a gag and nothing more. As Robert Zemeckis put it, Back to the Future’s success meant a sequel was inevitable.
“We’d never designed the first Back To The Future to have a sequel. The flying car at the end was a joke, a great payoff. We thought this would be really hard to unravel and do again. But when you make a movie that’s as successful as Back To The Future, it becomes this piece of corporate real estate. It becomes bigger than you as a filmmaker. You’re basically given a decision: we’re making a sequel, do you want to be involved in it or not?”
2. Carl Sagan was a fan of the movie’s science. I can’t speak for how Neil DeGrasse Tyson feels about the movie, but Carl Sagan was a fan. The astronomer had nothing but praise for Robert Zemeckis on how he handled the multiple timelines. The guy was such a fan of the movie that he agreed to appear in a 1990 Earth Day special that featured Christopher Lloyd as Doc Brown, and moonlights as the alias used by Doc in Back to the Future: The Game.
3. The sequel was supposed to send Marty back to the 1960s. Rather than transport Marty from the future back to 1955 again, Bob Gale’s first treatment had Marty going back to 1967. Bob told Empire that he wanted Lorraine to be a hippie.
“The third act of the movie, rather than going back to 1955, took Marty to 1967. Biff ended up with the sports almanac in 1967 because I thought it would be cool to do the ’60s. George McFly would have been a college professor, Lorraine is a flower child. Let’s do this stuff in the ’60s and see what we could do with that.”
4. Elijah Wood made his feature film debut in the movie. The movie marked Elijah’s first role in a film with his appearance as one of the kids playing an arcade game that Marty interacts with in the diner at the beginning of the movie.
5. Michael J. Fox had to relearn how to skateboard. One of the first film’s most iconic action sequences had Marty grabbing a kid’s scooter, ripping off the wooden handlebars, and skateboarding through 1955 Hill Valley with Biff trying to run him over. The sequel — as well as the third movie filmed at the same time — were shot five years later and Michael J. Fox had forgotten how to skate. The actor had to re-learn in order to look convincing in the sequel’s hoverboard scenes that had him in a harness hanging from wires.