Visible crew/equipment: After explosion and the flour wagon runs driverless spilling the flour barrels you can see a man through an opening under the seat driving.
Continuity mistake: When Lomax takes the first two bags of gold from the war wagon, John Wayne opens the gold, reaching in and some spills out. Next shot, putting it back in, none has spilled.
Other mistake: When Lomax enters the War Wagon after it has overturned, the safe door is already partially opened.