It's one of the best time travel franchises ever made and a rare gem of a film that people from different age groups and different backgrounds can all appreciate. But even if you can recite all of Doc & Marty's conversations because you've seen it so many times, chances are you still don't know all of these juicy trivia bits.
It Was Set In the Fifties For Simplicity's Sake
The fifties were chosen for the past setting not because writers Robert Zemeckis and Bob Gale had a soft spot for the era, but instead because they were easy. Essentially, the two wanted to make a time travel story that didn't require knowledge of the past to enjoy it. They figured the fifties would be far enough back that it would seem like a different setting, but still allow the main character to connect with people that he knew from his regular life.
The DeLorean Could Have Been A Refrigerator
It took the writers a while to come up with the perfect time machine. In fact, at one point they thought it would be cool to use a refrigerator that had to be powered by an atomic explosion to return home -until they started worrying that kids would lock themselves into them. Spielberg ended up using this idea as inspiration for Indiana Jones' nuclear safe-guard in Kingdom of the Crystal Skull.
Ultimately, they decided on a DeLorean because the stainless steel construction seemed like a good method for flux dispersal during time displacement. Three DeLoreans were purchased for the original and another three were bought for the sequels. After the film's release, Bob Gale and Robert Zemeckis received a letter from John DeLorean thanking them for using his car in the movie.
It Was Both Too Tame and Too Controversial
Robert Zemeckis had to hit up quite a few studios while trying to sell the film. Since the biggest comedies at the time were much more raunchy, like Fast Times at Ridgemont High and Revenge of the Nerds, a lot of studios turned down the idea because it wasn't risque enough. But then when Zemeckis took his idea to Disney, they rejected the story because they thought it was too scandalous to have a mother fall in love with her son.