Factual error: At several points during the film, characters are shown loading brass cartridges into their revolvers. The revolvers shown throughout the film, however, are "cap and ball" models, which were hand loaded and could not be loaded with cartridges. Note the loading levers under the barrels - cartridge revolvers do not have these.

Continuity: After Pierce Brosnan does the deal for the bullet, Anjelica Huston rides off with his horse attached to her carriage. Only problem is we see the entire exchange, and at no point does anyone tie the horse on.

Factual error: The movie takes place in 1868, and every guy and his dog are wielding cartridge conversion Army, Navy, and even what appears to be Walker colts. Unfortunately, such conversions were not performed until 1869, after Smith and Wesson's rights to the Rollin White patent expired.