1.The script was rejected over 40 times and by every studio.
2.Bob Gale, who co-wrote the script, was inspired to write the story after seeing his father's high school yearbook while visiting him.
3.In the original script the time machine was NOT the iconic DeLorean, but rather a refrigerator.
4.In the refrigerator version of the script, Marty McFly, in a rather dark turn, accidentally time-travels while attempting suicide.
5.The producers decided to use a DeLorean as the time machine in order to keep the joke in the film that it was a UFO.
6.Production designers chose 88 m.p.h. as the speed to achieve time travel because they thought it looked good on the digital speedometer.
7.The lighting hitting the clocktower storyline/scene was added in order to save money.
8.Sid Sheinberg, then-head of Universal Pictures, suggested that they change the name of the movie to Spaceman From Pluto, because he believed a movie with the word "future" in the title would not do well.
Even though Sheinberg was serious the title change — which referenced the barnyard scene in the film where Mr. Peabody mistakes the DeLorean for a UFO — Spielberg played it off as a joke in order to keep the title.
9.Doc Brown was supposed to have a pet chimpanzee named Shemp, instead of his dog Einstein.
10.The set used for Hill Valley had previously appeared in two other iconic movies: To Kill a Mockingbird and Gremlins.
11.When Christopher Lloyd was told that Eric Stolz — who was infamously cast as Marty — was let go, he reportedly had no idea who they were talking about; he had been calling him Marty the entire time and thought that was his name.