Factual error: The rifles that Jake Cutter has Paul Regret dig up are Henry repeaters, or possibly 1866 Winchesters. Either way weapons unavailable in the period depicted in the movie.
Factual error: In the first match between Fast Eddie and Minnesota Fats towards the beginning of the film, Eddie, right after declaring he would start to win after losing thus far, shoots the one ball into the side pocket by shooting the cue into a striped ball. Sharp eyes will notice that he actually hits THROUGH the cue and strikes the stripe into the one with his stick. While a nice trick, this is an incredibly illegal shot and would never have been allowed.
Factual error: Delilah is shown stirring a pot of ears of corn. Corn was not known until native Americans introduced it to settlers in North America in the 16th century.