Continuity mistake: 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.
Character mistake: When Schaeffer, McFee, and Fergie walk down the dusty road to Amish village, Western gunslinger style, they make a silly mistake no cop would make - they assume that Amish villages are unarmed and undefended. No so. The Amish have no prohibition on guns and almost every house would have at least one hunting rifle or shotgun. The three bad guys are risking being shot to bits before they get halfway down that hill; they don't even make an attempt at concealment. (Wouldn't they also at least think John - a police officer - would still have his gun or might have got hold of a firearm from the Amish?)
Continuity mistake: When the local bums provoke the Amish, Viggo Mortensen's hat is grabbed twice - for the first time when the leader of the gang smears Alexander Godunov's face with ice cream, the curly-haired guy can be seen swiftly grabbing Mortensen's hat in the background. Thereafter Mortensen is hatless - until the same curly-headed bum grabs his hat again, now in the wide shot.
Continuity mistake: When Samuel shows his new toy to Rachel she looks out of the kitchen window into the fields. Two shots later she looks out of the same window and, surprise, there are Eli and John putting up the bird house. When she talks to Eli later there is same window in the background, with no bird house to be seen.