Factual error: At the end of the train scene just before Marty travels to 1985, the train busts through a road block warning that there's only 1/4 mile of track left before the ravine. Keep in mind that the train is travelling at approximately 70-80 mph by this time. At 70 mph (and not even accelerating) it would only take the train 13 seconds to reach the ravine. The actual time in the movie is at least a minute. (01:40:31)
Suggested correction: This can't really be classed as a factual error because we don't know how much of the track has been built since that barrier was put up. They could've put that barrier up when there was only 440 yards or so of track left, but have laid another 800 yards of track since then. I myself actually work on the roads; if we're resurfacing a road, we don't move the sign 100 yards further up the road every time we've resurfaced 100 yards. That sign stays there till we're done, regardless of the distance.
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.
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.
Deliberate mistake: In the duel with Marty, when Tannen gets fancy spinning his gun, when he places it in the holster the grip is facing forward. They then use effects to turn the gun so the grip is facing back. (01:26:44)
Suggested correction: No, the gun is spinning on his finger and goes into the holster with the grip facing towards the back, which is completely consistent with the spin of the gun.
