Revealing mistake: When our heroes are on the conveyor belt which carries the rocks towards the spinning saw blades, the rocks which get cut in two are seen to be cut before they reach the blades. (01:20:45)
Revealing mistake: When our heroes are on the conveyor belt heading towards the saw blades, it's obvious that the conveyor belt on the other side of the blades is just a painted backdrop. (01:20:45)
Visible crew/equipment: In the first shot of our heroes being given their assignment, something, presumably a crew member, can be seen intruding into the frame to the right of Barbara Windsor and casting a shadow on the desk. (00:11:50)
Other mistake: When our heroes are on the conveyor belt in the rock-processing plant, none of the rocks are larger than two feet in size - especially having gone past a set of spinning saw blades - and yet they get sprayed by two steam nozzles, the highest of which is about six feet in the air, and the lowest is about four feet in the air. Clearly neither of these nozzles would have any practical use. (01:21:10)
