1. President Ronald Reagan quoted the film in his 1986 State of the Union speech, saying, "never has there been a more exciting time to be alive — a time of rousing wonder and heroic achievement. As they said in the film Back to the Future, 'Where we're going, we don't need roads.'"
2. When President Reagan saw the scene where Doc Brown laughs in disbelief over Marty McFly informing him that Ronald Reagan "the actor" was president in 1985 he enjoyed it so much that he asked the projectionist to replay it.
3. Huey Lewis, who provided "Power of Love" and "Back in Time" to the film's soundtrack, is the judge in the battle of the bands scene who tells McFly that his music is "too darn loud."
4. John DeLorean sent a fan letter to writers Bob Gale and Robert Zemeckis thanking them for "keeping my dream alive" by using his car in the movies.
5. Universal Studios head Sid Sheinberg didn't like the film's name because he didn't think anyone would watch a film with the word "future" in the title, and wanted it changed to "Spaceman From Pluto."
6. However Sheinberg had some great ideas as well — he was responsible for changing "Professor" Brown to "Doc" Brown and vetoing Brown having a chimpanzee as a pet in favor of a dog. He claimed, "You have to get rid of that chimp because no one's going to see a film with a chimp in it."
7. There is a sticker on Doc Brown's truck that says, "One nuclear bomb can ruin your whole day. "
8. Ralph Macchio turned down the role of Marty McFly.
9. Biff's catchphrases "Make like a tree and get out of here" and "butthead" were improvised.
10. Thomas F. Wilson, who played Biff Tannen in the BTTF series, used to carry around a postcard of frequently asked questions to give to fans.
11. In the opening title sequence, there is a picture of Harold Lloyd hanging from the clock tower from the silent film Safety Last!, which foreshadows the climax of the first film.
12. Claudia Wells, who played Jennifer Parker in the first film, gave up her role when her mother was diagnosed with cancer. Elisabeth Shue replaced her for the last two films.
13. Crispin Glover lost his voice due to nervousness while filming. Some of his lines needed to be dubbed over after shooting.
14. Glover said he got into a feud with the studio about his salary for Back to the Future II because the studio was going to pay him a salary less than half that of Lea Thompson (Lorraine) and Tom Wilson (Biff). When he refused to accept the salary, the studio proceeded without him, casting a new actor and using archived footage from the first film as well as prosthetics to duplicate his likeness. Glover sued the studio and it was settled out of court.
15. According to Zemeckis and Hale, the script was rejected over 40 times by every major studio. Studios told them that time travel movies didn't make any money and that the movie was too sweet.
16. Disney rejected the movie because the oedipal plot line of Lorraine falling in love with Marty was too incestual for the Mickey Mouse studio.
17. Promotional sunglasses for Back to the Future II were sold at Pizza Hut.
18. In the second draft of the script for Back to the Future the time machine is a "time chamber" that looks like a refrigerator.
19. When Marty looks into the window of the antiques shop in 2015, you can see a stuffed animal of Roger Rabbit, whose movie was also directed by Robert Zemeckis.
20. Also, the movie theater in 2015 is screening Jaws 19 by Max Spielberg — Steven's son.
21. Michael J. Fox was still a full-time cast member on Family Ties when filming Back to the Future. He filmed most of his scenes for Back to the Future at nights and on the weekends.
22. Johnny Depp read for Marty McFly, but the producer Bob Gale doesn't even remember him reading for the part.
23. There is a homage to Stanley Kubrick's Dr. Strangelove at the beginning of the film when Marty hooks up his guitar to Doc's CRM-114 speaker system — something frequently referenced in Kubrick films.
24. The Back to the Future trilogy included the screen debuts of Elijah Wood and Bill "cool dude" Zane.
25. In the French version of the film, Marty McFly is called Pierre Cardin in 1955.
26. In the Spanish version of the film, Marty is called Levi Strauss.
27. Flea, the bassist from the Red Hot Chili Peppers, makes an appearance as Needles, Marty's boss in 2015.
28. When Marty departs 1985, he leaves the Twin Pines Mall, and then knocks over a pine tree when he arrives in 1955, at the Twin Pines Ranch. When he returns to 1985, the shopping center is called Lone Pine Mall.
29. The band in Back to the Future III is ZZ Top.
30. Michael J. Fox actually lost consciousness after getting caught in the ropes when "Mad Dog" Tannen attempts to hang Marty in Back to the Future III.
31. They had to ask Clint Eastwood for permission to use his name as Marty's 1885 alter ego.
32. Carl Sagan considered Back to the Future II the best movie ever made based on the science of time travel.
33. Melora Hardin, best known as Jan from The Office, was at one point cast to play Marty's girlfriend Jennifer, but she had to be replaced when they decided she was too tall for Michael J. Fox.
34. In 2011, 1,500 Nike MAG sneakers were auctioned on eBay in support of the Parkinson's Research Foundation. The first pair sold to rapper Tinie Tempah for $37,500.
35. In the scene when Marty sees his future family, Michael J. Fox plays actually plays four characters: himself, future Marty, Marty Jr., and Marlene.
36. Nike plans to release Nike MAG sneakers with auto-lacing ability in 2015.
37. Doc Brown's "futuristic" shirt in Back to the Future II, which features a man on a horse chasing a train, coyly hints at the climax of Back to the Future III.
38. The trailer for Back to the Future III was at the end of Back to the Future II. Both movies were filmed in a 11-month span with only a three-week break in between films.
39. Doc Brown's kiss with Clara Clayton in Back to the Future III was the first on-screen kiss in Christopher Lloyd's acting career, by which point he had 46 acting credits spanning over 15 years — he was 48 years old.
Correction
Item #11 originally stated that the picture in the opening title sequence of a man hanging from the clock tower was Doc Brown. The photo is actually an iconic scene from the 1923 silent film Safety Last! starring Harold Lloyd.