During the mine shaft cave-in during and after the ore is removed, a large vertical chuck of rock is shown breaking away from the shaft wall and collapsing twice.
As the stand-ins for 'The Dutchman' and McBain are riding in the wagon on their way to rob the Lisbon mine, the long shots show 'The Dutchman' wearing a tan leather jacket. However, on reaching the mine, the jacket has disappeared and is replaced by a vest.
At the beginning of the movie a group of prisoners chained in tandem with leg irons shuffles its way to the river for a "bath". As they approach the guard at the water's edge they are handed a bar of soap. the second prisoner in line holds out his left hand and is given a bar of soap. In the next scene this prisoner has no soap and holds out his hand again to receive the bar a second time.
The first time Van Hoek and McBain walk to Vincente's house at night, the moon is shining brightly. But when they get to Vincente's front door, it is pitch dark.
45 minutes into the film, Mac is shaving and stops to talk with Anita. He still has shaving cream on his right cheek. After he hands her some money, the shaving cream disappears.
Right when they are leaving the collapsed mine, two people are visible, one in a white shirt, next to the corner of the adobe building in the background. They quickly get back behind the building.
At the time setting of this film, gold was fixed at a price of $20.67 per ounce. $100,000 of gold would then equate to over 302 pounds of the pure metal. But, they are stealing gold-bearing ore. The richest known hard rock gold deposits yield 1.5 ounces per ton of ore. So, they would have to steal thousands of tons of ore, not just the few sacks shown in this film.