Corrected entry: Just before the train hits the inside of the ravine, the train explodes. It shouldn't just explode in midair.
Corrected entry: At the end of the film, Jennifer has the fax from the second movie saying 'You're Fired'. Then, because Marty stood up to Needles, the message erased. However, Jennifer still has the piece of paper. If Marty didn't get fired in 2015, then there would be no fax, and therefore no piece of paper at all. Jennifer shouldn't have had the piece of paper.
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.
Corrected entry: In the scene at the start of the movie, the time machine is flying 50 feet or so in the air when it is struck by lightning and sent back to 1885. Later in the movie, we learn that the lightning destroyed the flying circuits. Assuming this is true, as soon as the time machine appeared in 1885, it would have fallen to the ground and been destroyed.
Corrected entry: When Doc and Marty find the Delorean in the mine, the tires have rotted off with time. It seems that all they had to do to run the car again was replace the tires. However, as any mechanic will know, in that amount of time not just the tires would have rotted. Every rubber hose and gasket, every piece of wire insulation, every bushing and grommet, and many other parts in the car would also need to be replaced. There would be no way to run the car short of completely rebuilding it.
Corrected entry: Doc begins telling Marty about his accident with Rolls-Royce, before stopping himself and telling Marty it's better that he doesn't know. How exactly did Doc find out about the Rolls-Royce incident in the first place? When Doc was in the year 2015, he didn't actually talk to Marty or any of his family or Needles, so who told him about the Rolls-Royce incident? At that point, it had happened 30 years prior, so it's doubtful that a minor car crash from 1985 would still be the talk of the town in 2015.
Corrected entry: During the train sequence, when it's pushing the DeLorean, there is a wide shot of the green steam coming out of the train. The steam looks computer generated because it is far too bright and appears slightly away from the train. (01:36:40)
Corrected entry: When Marty finally returns back to 1985 on the finished train track the ravine has been renamed in honor of his alias "Clint Eastwood." But why? The townspeople wouldn't know it was him on the train and Doc wouldn't have been so foolish as to tell anyone "Clint" hijacked the train after becoming a hero from the Tannen fight. It should have still been called Shonash Ravine.
Corrected entry: When Marty asks the Doc if they can take Clara with them to the future, the Doc says no, because you mustn't tamper with the time continuum for your own benefits. However, in the second film, he does change the continuum for Marty and Jennifer's benefits, by going with Marty and Jennifer to change the future, so their son wouldn't go to jail.
Corrected entry: The jacket suit that Biff wears in the garage scene in 1985 in Part 3 is red and gray. It is green and gray in the other films.
Corrected entry: When the train is pushing the DeLorean and "Clara" on the train and trying to get to Doc, Marty is in the driver's seat, then the next shot he's in the passenger seat to where he passes the hover board to Doc, then when Marty passes through time to Eastwood Ravine he's back in the driver's seat.
Corrected entry: Doc is always banging on about making as little impact as possible in his new life as an inhabitant of 1885, yet the method of exit he chooses will change hundreds of lives and cause huge disruptions to all sorts of timelines. The train they destroy would not have been easy to replace, and would have been used by hundreds, maybe thousands of travelers to get to places they are now not going to get to, to meet people they are now not going to meet, to start family lines that now don't exist, and so on on so on. Now that Buford is no longer a threat, a far better alternative would be for Marty and Doc to leave town and live quiet, anonymous lives somewhere isolated - something Doc has already thought of and a far better idea than their returning to the future in such a damaging manner.
Corrected entry: At the onset of the film, Doc and Marty discover Doc's grave from 1885 with the dedication by Clara Clayton on it. Now remember, this was before Marty had gone back to 1885 to meet Doc and further influence the happenings in that year, which included their chance meeting with Clara when she almost died. Even without Marty's influence in 1885, history of the film series up to that point said Clara went over the cliff and died. So therefore, it is inconceiveable that Clara could have lived to even meet Doc to put the dedication on his grave, as he died a few days after she would have.