Factual error: During the scene towards the end of the film where Alejandro is chasing Captain Love in the shack with the furnace at the mine, we see a pressure gauge just before the furnace explodes. The unit of measurement on the pressure gauge is shown as kg/cm2. Metric measures were not used in Mexico until eleven years after the film was set, and as California was a part of Mexico at the time, metric measurements would not have been used there.
Factual error: The movie takes place 20 years after 1821 which would be in the year 1841. There is a line that says that Santa Anna is at war with the United States. But the Mexican war did not break out until 1846. Santa Anna was not at war with the U.S. in 1841.
Factual error: The film takes place during the 1840s and features an American Army officer, Capt. Love. The western style hat that Love wears with the crossed swords insignia of the infantry was not used by the US Army until the American Civil War, twenty years later. During the time period of the film, US Army officers wore a soft cap with a bill in front.
Factual error: Captain Love's revolver is a Colt Buntline. This model wasn't released until 1876. The movie is set in 1841. He should have been using a Colt Paterson, which was invented in 1836.
Suggested correction: The pistol that Captain Love is using IS the Colt Paterson. You can see this by going to timestamp 1:58:17. If you look at the profile of the weapon in his hand and compare it to pictures of the Colt Paterson, you can see it is a Colt Paterson. The Colt Buntline does not have the same profile.
At the end of the movie Captain Love does have a Colt Paterson, but in the beginning of the movie the pistol he has is a different model. The first pistol looks a lot like a Colt Buntline.