Witness (1985) - 4 major mistakes

Continuity: When Harrison Ford confronts (and beats up) the tourists, there are a number of close-up shots of the people in the first wagon, including one where Viggo Mortensen leans forward and tells the driver to do nothing, even though he is being provoked. In all these close ups, Mortensen is bare-headed. When the shot changes to Ford's perspective, from the cart behind, we see one of the tourists grab a straw hat from Mortensen's head. The hat has appeared out of nowhere in a split second. There is a child with a straw hat behind Mortensen, but the hat stays on his head in both shots.

Plot hole: When Schaeffer, McFee, and Fergie drive to the Lapp farm to kill John, the car stops on top of a hill. Then it reverses a bit to be out of sight from the farm. But then the formerly careful guys get out and walk down the open road, sporting their guns like in an Italo western.

Plot hole: When John tries to start his car with the flat battery the least he should have done is switch the windshield wipers off.

Continuity: When the people are having their break during the barn raise there is a panorama shot where most of the roof is gone that had been already fixed.