Character mistake: At the ravine, upon learning that the bridge doesn't exist yet, Marty states to Doc "We can't wait a year and a half for this to be built". If you carefully look at the sign, it says the bridge is opening Summer 1886. That's under a year away, not a year and a half from Sept. 1885.
Back to the Future Part III (1990)
1 character mistake - chronological order
Directed by: Robert Zemeckis
Starring: Christopher Lloyd, Michael J. Fox, Mary Steenburgen, Lea Thompson, Thomas F. Wilson, Elizabeth Shue
Factual error: Though extremely modest by today's standards, the dress worn by Clara at the hoedown shows far too much cleavage for the time. No schoolteacher would ever wear a dress like that in the 1880s.
Marty McFly: Hey, Doc! Where you goin' now? Back to the future?
Doc: Nope. Already been there.
Trivia: Director Robert Zemeckis asked for Clint Eastwood's permission to use his name for BTTF 3. Clint Eastwood felt so honored that he said yes.
Question: Doc has always been firm about not wanting to create some sort of paradox. Was he not at all worried that eventually someone would go into his barn looking for him and find his giant refrigerator and his model railway with the car that said "TIME MACHINE" on it? I know he stayed behind after he rescued Clara so could have removed all that, but the original plan was he was going to hop into the DeLorean with Marty. We know he definitely left the model railway there as Clara picked the car up which prompted her to go after him.
Answer: Well everyone in that town knows Doc's a pretty smart guy. Chances are he was doing some experimenting with time machines or something. The average person I'm sure would never figure it out anyways or think it was a crazy irrelevant project. Clara only figured it out because Doc told her about the time machine and time travel and thought Doc was lying to break up with her. The story sounded crazy until she saw the model, then saw the machine and realised he was telling her the truth. But the average person in that period knows nothing about the time machine, cars, or rime travel and even if they by some chance figured out Doc was from the future nobody would believe it nor could they prove it.
Answer: Someone would go into his barn and do what? See a sign that says time machine and believe it and then use it? Seems highly unlikely.
lionhead