Other mistake: When the Major shoots the rope out from under the slow soldier, the rounds should have gone through the floor but did not. There aren't even marks on the floor.
Other mistake: The copyright date is 1967. In the final title frame at the end of the movie, the copyright date in Roman numerals is incorrect. The V and the X are inverted. It reads MCMLVXII. The correct Roman numeral is MCMLXVII.
Other mistake: When Spencer Tracy is shaving someone's arm appears onscreen at the right. (01:07:12)
Other mistake: When the convoy of getaway vehicles arrive at the scrap yard, after dropping the loot of at the airfield, two of the jeep type vehicles have the same registration number - 247EJF.
Other mistake: The villain's plan is to impersonate along with his large crew a platoon of the Mexican army. He already captured the soldiers and has them incapacitated, all he needs to do is take their uniforms. Instead of doing so, though, he mows down the whole lot with a heavy machinegun. When it's time to put on the show, everyone wears nice and tidy white uniforms.
Other mistake: King Arthur is on the far right of the scene as Guinevere is led away by the guards and he nods at someone off camera, asking them if it's OK to start acting as the camera moves around.