Continuity mistake: Blue's arms at the jail cell window instantly switch back and forth from being together to apart to together.
Revealing mistake: The square base securing the knife sticking out of the abdomen of the army lieutenant is visible as he and Blue scuffle in the river.
Revealing mistake: At the end, El Tigre (Ricardo Montalban) is supposedly dead, draped over the horse as his brother leads them away. However, his right foot is in the stirrup, and it is obviously holding his weight...not dangling as the rest of the "corpse"