Anacronismi: In a conversation between Avram and Tommy there is a reference to the country of Czechoslovakia. The film is set in 1850 but Czechoslovakia was established in 1918 as a result of WW1.
Factual errors: The Jewish Sabbath does not necessarily end when the sun goes down, but when it gets dark which could be up to an hour later. Also, an observant Jew would not be able to travel outside a city on Sabbath, even on foot, for more than 2,000 biblical "cubits" (~1,000 yards) from the place he was in when Sabbath began. Therefore, Avram would not have been willing to travel, leading his horse, on Sabbath.
Continuity: Avram cocks his gun after tripping Matt Diggs during the gunfight in San Francisco but in the next shot, the hammer isn't pulled back.
Anacronismi: Avram tells Tommy that he wants Tommy as his best man at the wedding. There is no place in the traditional Jewish wedding ceremony for a best man. It has been added by some in recent times, but in 1850, Avram would have had no idea what one was.
Audio/video fuori sincrono: When Avram's horse gets spooked by the rattlesnake, Avram begins yelling but his mouth doesn't move.
Anacronismi: The movie is set in 1850, and in the early scenes (probably in Pennsylvania with the Amish community) there are barbed wire fences lining the roads. Barbed wire wasn't invented until 1873 (earlier versions might have been available but were not mass produced and certainly not for that long of a stretch) and was intended mainly for the western United States, not the eastern half.
Errori geografici: After reaching the Coast of California, Avram and Tommy must travel a day-and-a-half North to reach San Francisco. In one of the next scenes they are shown riding with the ocean on their right-hand side. That would have had them riding South.
Anacronismi: The movie takes place in 1850. Tommy Lillard holds up a Wells Fargo office in a frontier town; Wells Fargo wasn't founded until 1852.
Anacronismi: Several characters use the Colt Army .44 cal pistol. This wasn't developed until 1860. Also, during the final gun fight, Matt Diggs gives the rabbi a Remington New Model Army .44 cal pistol. This didn't come out until 1858.
Factual errors: After the final gun fight scene, the rabbi drops three balls from the rear of Matt Diggs' pistol. With the 1860 Colt Army .44, the balls must be rammed into the front of the cylinder with the loading lever. They will not fall out.
Anacronismi: When the native Americans are manhandling Tommy at their village, one of the Indians is clearly wearing a gold wristwatch on an expanding metal strap. See it at 1:03:12 on the Region 1 DVD.
Continuity: After he is first robbed, when Avram walks down the road picking up the things strewn from the wagon, the order he finds them does not match the (reverse) order as they were thrown.
Factual errors: In Judaism, a person is not only allowed but required to break the Sabbath if a person's life will be in danger if they do not break it. When the posse is chasing Avram and Tommy, both their lives are in danger, and Avram would have had to have jumped on his horse until they were out of danger.
Errors made by characters (possibly deliberate errors by the filmmakers): Any factual errors Avram commits regarding traveling on the Sabbath could be an intentional character trait, in keeping with how poor of a student he was at the yeshiva.
Errors made by characters (possibly deliberate errors by the filmmakers): At the end of the opening credits, Avram holds up his suitcase and says, "This you couldn't throw out first?". If that is the last item on the road, then it makes sense that the suitcase actually was the first item the robbers threw out of the wagon.
Anacronismi: The road Avram is walking down at the beginning of the movie is clearly a modern gravel road for automobile traffic.