- Deleted Scene:
- After excavating the DeLorean, Marty and the 1955 Doc touch the tires which suddenly turn to dust, which is why Doc looks at one of its wheels as it's being put onto the tow-truck.
- Just before Marty goes back to 1885, 1955 Doc offers Marty a pistol to take with him, and Marty turns him down. It's the same pistol that Doc uses as a starter pistol a few seconds later.
- Marshall Strickland confronts Buford and his gang on their way to confront Marty. Strickland lets them go until Buford shoots him in the back, killing him, saying "I Lied!" before riding off. Before he dies, Strickland tells his son "Remember that word, discipline..." The producers thought it was too depressing, and after such a despicable deed, it didn't seem right that Buford not die. They were worried it would make audiences want Marty to kill Buford, and he can't, because Buford needs to live long enough to extend the Tannen family line to get to Biff. It explains why Strickland's deputy, now wearing a Marshall's badge, arrests Buford and his gang, with the line "You're under arrest for the murder of Marshall Strickland" redubbed to "You're under arrest for robbing the Pine City stage!"
- In the script and novelization the scene where they have horses drag the DeLorean is longer, with Marty speculating that since the engine is rated at over 100 horsepower, they might need 100 horses. Doc then goes on to explain how the concept of horsepower doesn't really map to reality.
- Fake Irish: Seamus and Maggie McFly.
- Hey, It's That Place!: The location used for the 1885 Hill Valley is the same location used for the 1985 Clint Eastwood film Pale Rider. Amusingly, Pale Rider had been knocked out at the box office by the first BTTF film.
- Missing Trailer Scene:
- From the preview at the end of Part II, there's Doc's line of "Just try it, Tannen!"
- The film also uses an alternate audio recording of Thomas F. Wilson as Buford shooting at Marty's feet and saying, "Come on, runt! You can dance better than that!"
- Refitted for Sequel: It's widely known that the time machine was originally a chamber (specifically a refrigerator), and in order to travel through time, Doc and Marty would've sneaked into a nuclear test site in the desert to get the necessary 1.21 gigawatts. In this film, Doc sends Marty to 1885 at a drive-in theater in the desert.
- So My Kids Can Watch: Mary Steenburgen signed on because her children begged her. This was quite fortunate for the filmmakers, who regarded her as their first and only choice for the part.
- What Could Have Been:
- In the scene where Marty flips the spittoon onto Buford, he was originally supposed to have flipped some stray manure. However, stunt coordinator Walter Scott, who actually had grown up in the rural areas of the west, and actually moved his family out there, pointed out to the Bobs that in the old west, people frequently got covered in manure all the time and never complained at all, a fact that the Bobs, two self-professed city guys, never knew.
- Ronald Reagan as the 1885 Mayor. Given the moment dropping his name in Part I and the Max Headroom Expy that appears in the 80s Cafe in Part II, having him appear in Part III would have neatly tied things together in a Rule of Cool way. And Part III was The Western, a genre Reagan worked with.
- If Crispin Glover had signed on to the sequels (various reasons have circulated over the years as to why), he would've played Seamus McFly in Part III, and Lea Thompson would play a bar girl who eventually marries Seamus. Also, Seamus offers Mad Dog a job after losing to Marty.
- In the script, a heartbroken Doc drank the whole bottle. Looks like he can hold his liquor... until Marty comes to get him.
- Working Title: The film's working title was Three.
Trivia / Back to the Future Part III