Pancho puts the short (and fourth) candle on the table to the left of the other three. But when he and Doc Reuben go to move the table, the short candle is now second from the left.
The school bus towards the end of the film is a 1957 Ford with single headlights; later, when it's running at high speed down the mountain, it's a 1958 Ford with dual headlights, then changes back to a 1957 Ford again.
The amount of black grimy dirt on the yellow jeep from the mining company Pancho and Reuben start driving to town in changes from scene to scene. The vehicle seems to get cleaner, then dirtier, then cleaner again.
When the two men from the mining camp who are in pursuit of Reuben and Pancho come across the fallen bridge, the camera pans the span, the shot freezes, then the film is obviously run backwards for some reason - possibly just to lengthen the take a couple seconds.
At 26 minutes in, the sound of breaking glass is heard when Glenn Ford bumps his head into a hanging lamp, even though the bulb is clearly left intact.