Other mistake: The title sequence reads, "Base on the novel Red Alert" instead of "Based on the novel Red Alert" (00:02:20)
Other mistake: When Col. Bat Guano shoots the Coke machine and it squirts him in the face, he's holding his head too high. You can see that he first gets the spray on the chin and then he ducks down to take it full in the face. (01:09:50)
Other mistake: When the B52 is attacked by a missile, the DSO orders "Commence evasive action right". The course of the missile on the radar screen remains straight, while the heading of the missile should change as seen from the turning plane. (00:59:30)
Other mistake: During the missile attack on the bomber, the radar operator is calling out closing distances to the approaching weapon and they are consistent with the 10 mile calibration rings on his scope. As the missile gets around the 20 mile range, the distances he reports are no longer consistent with the scope.
Other mistake: When the radio operator opens the Aircraft Communications Codes book, he turns first to a 'L' page, but all the codes are 'F' codes including the key code. He then turns to a 'J' page and again the codes are the same 'F' codes. He then turns three 'E' pages, pages one and three are identical.
Answer: Peter Sellers improvised it. During that scene if you watch the actor playing the Russian character you can see him trying not to laugh at Seller's performance.