1. The script was rejected by every studio for more than 40 times.
2. The co-writer of the script, Bob Gale, was inspired to write the story after he saw his father’s high school yearbook.
3. In the original script, a refrigerator was used as the time machine instead of the iconic DeLorean.
4. In the script where the fridge is the time machine, the main character, Marty McFly attempted to commit suicide and climbed inside the time machine.
5. In order to keep the joke in the film, the producers decided to use the DeLorean as a time machine believing it was a UFO.
6. Production designers thought it looked good in digital speedometer to assign 88mph as the speed to obtain time travel.
7. To save some money, the scene about the lightning hitting the clock tower was added.
8. Changing the name of the movie to Spaceman From Pluto was suggested by the head of Universal Pictures, Sid Sheinberg believing that it won’t go well if the movie title has a word “future” in it.
9. Instead of Doc Brown’s pet, Einstein, the supposed pet in the movie is a chimpanzee named Shemp.
10. The setting used for Hill Valley previously appeared in two other famous movies, Gremlins and To Kill A Mockingbird.
11. When Christopher Lloyd was told that Eriz Stolz, who was cast as Marty was let go, he reportedly wasn’t aware who they’re talking about since they have been calling him Marty and thought that it was his real name.
12. At that time, Michael J. Fox was a main actor in a sitcom which made Lea Thompson upset about the recasting.
13. Most scenes in the movie were shot at night, in order to accommodate Fox’s commitment on his TV show, Family Ties.
14. Fox was so deprived of sleep that he had freaked out during the taping of Family Ties, that he looked for a camera prop at the backstage thinking he was in a set for the Back to the Future.
15. Fox told that he really hated filming inside the DeLorean because of the position of the time circuit box was so sharp that he cut his hand every time he changed gears.
16. There is an actual backstory of how Doc and Marty became friends. When Marty was only about 13 or 14 years old, Doc caught him in his laboratory and offered him a part-time job.
17. Crispin Glover hated the ending of the movie because he thought it will convey a message that the McFlys were happy only because they had money.
18. Zemeckis and Gale never intended to make a sequel/s to the movie for they thought to be more of a joke to have an open-ended ending with the flying De Lorean.
19. Zemeckis once said that there will NEVER be a sequel, reboot or remake of the movie in his entire life.
Source: Buzzfeed
