Corrected entry: Near the end, when Needles challenges Marty to a street race, the smartest thing for Marty to have done was nothing. By speeding away in reverse, he could have just as easily hit another car behind him, with the subsequent chain of events leading, more or less, to the future that Jennifer witnessed in 2015.
Factual error: In 1885, Hill Valley and its surrounding areas are shown as having a desert climate, when in both 1955 and 1985, the climate is grassland. In reality, Nevada County, California (where Hill Valley is supposed to be located) is and always has been grassland and forests, not arid desert.
Suggested correction: Hill Valley is in Hill County, as stated at the activation of the clock in 1885.
Plot hole: Although Marty rips the fuel line, not all the fuel would have drained out of the tank. Only the fuel that was already in the fuel line would have leaked out, meaning it could simply be patched, bled and the engine would run without a problem.
Suggested correction: A cut fuel line could absolutely drain the tank. Even if not a direct route with respect to gravity, it could still create a siphon effect and drain the tank.
Corrected entry: Doc Brown can build a time machine but is unable to figure out how to build a still to extract pure ethanol from Whisky in order to use as fuel for the DeLorean. He stated to Clara that he is a "student of all science" so this should include chemistry. Chemists know how to build a still. Doc, however, tried to fuel the car with strong Whisky without distilling it.
Correction: They did not have time to build anything, they were in a hurry to leave before Doc gets killed.
Correction: He would with no problem be able to get that thing to run on ethanol, just a different air fuel ratio bigger injectors so just make bigger holes in the ones you have. Just to run it one time would be no problem.
Corrected entry: Okay, we're going to get a bit deep here. Doc and Marty found Doc's grave in 1955. Doc sends Marty back to 1885 to rescue Doc. Now.....remember....all hinges around the image on the picture. Once the grave stone is broken in the fight with Mad Dog Tannen the image of the grave disappears in the photo. Wouldn't the picture disappear too? No grave in 1885 means no grave in 1955 which means no reason to take a picture in the first place. But then again....once the grave is broken then there would have been no grave in 1955 for Doc to see. Therefore he would have never sent Marty back in the first place. HENCE...once the grave was broken....the timeline is fixed and Doc of 1885 would live happily ever after with Clara, Doc of 1955 would just work on getting Marty home, and Marty would have disappeared from the 1885 timeline and things would have continued from when Doc and Marty are digging out the old DeLorean. Told you it was deep.
Correction: Marty took the picture of the grave BEFORE he went back to 1885 and changed the past, so there's no logical reason why the picture itself would disappear. Obviously, he wouldn't take a picture of nothing, but he had already taken the picture, which is why only the grave disappears.
Correction: For all we know, Marty could have been thinking of going back and convincing Doc to return to 1985 anyway, despite being told not to. The gravestone was probably a way of further motivating Marty's idea, but he could have wanted to go back in the first place after realising that he had no other choice.
Correction: Well, Marty didn't know about that future anyway, as Jennifer never told him she found out what caused his failure. Him reversing is a lot more like a definite change in character for Marty, rather than an attempt to change the future. That's what the scene was about. Next to that, he quickly spins the car around without coming to any intersection, so no immediate danger of running into someone.
lionhead