Ali Baba and the Forty Thieves (1944)

Revealing mistake: When Abdullah escapes his Mongolian pursuers by jumping his horse across the ravine, the horse kicks loose some debris at the edge. But the rocks simply disappear, indicating that the ravine is a painted set-up.

Trivia: Hulagu Khan (1217-1265) was the grandson of Genghis Khan, and the brother of Kublai Khan, perhaps the two most famous Mongol lords. He conquered Baghdad in 1255.