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: When Chris Farley is climbing up the side of the mountain to return the bird egg, you see the bottom of his moccasins and they appear to be made of a ribbed (for traction) material. Back then, they would have been made from animal hides and the bottoms would have been smooth not ribbed.