Back to the Future Part III (1990)

Continuity mistake: When the movie ends, Marty and Jen are blown away. They're either landing on shadowy or sunny grass, depending on the angle. This changes back and forth.

Sacha

Continuity mistake: When the movie is about to end and Marty and Jennifer walk by the tracks they have a bumper in front. Jennifer says "there's not much left", then the angle changes and the bumper has magically moved behind them.

Sacha

Continuity mistake: When the movie is about to end, Marty picks up Doc's photo. From the front shot he is grabbing it by the middle, but in the opposite angle he holds it by the lower end.

Sacha

Continuity mistake: After the breakfast machine dumps the eggs in the pot at the start, the eggshells disappear.

Continuity mistake: After visiting Seamus, Marty walks to the Hill Valley train station where a man is by the ticket window. In the next shot the man has disappeared.

Sacha

Other mistake: After Mad Dog tries to kill Marty at the bar, a man says "you better run, squirrel." Marty is crouched, 4 meters away from the counter, but in half a second he has managed to stand up, run to the counter, jump on it and run towards Buford.

Sacha

Deliberate mistake: When Marty drives towards the screen to go back to 1885, he passes by the same 5 speakers over and over again. It's obvious that the road was very short and they repeated the shots from many different angles to add-up for tension.

Sacha

Continuity mistake: When Marty and Doc are jumping on the logs on the train, the sun changes between shots.

Factual error: After Doc and Marty hijack the train, there are shots of them in the cab of the locomotive. Look closely behind them, there is a clip to hold a microphone for a 2-way radio or CB attached to the window post, which shouldn't be there in 1885.

Factual error: When the Indians are running from the cavalry they cross over a set of tire tracks. They are too far from where Marty started so cannot be his, and the lines can't be wagon tracks because the lines are too wide and the width is uniform. (00:19:30)

Continuity mistake: While Marty is fighting Tannen the sun changes between shots.

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.

Continuity mistake: Watch as Seamus hands Marty the baby, there is a definite "jump" and Marty is facing in almost completely the wrong direction, looking for a clue from the set's crew as to where he should be looking to catch the baby from... (00:24:20)

Continuity mistake: In the end scene where Doc's train comes back to 1985, Marty and Jennifer are literally blown away by the re-emergence of the train. While they are flying in mid-air, the front of the train is passing them by and gets just about to the cab (where the ELB is). However in the next cut, Marty and Jennifer are on the ground watching as the train just starts passing them again, and the train comes to rest at a point before the previous "blown away" cut scene.