Factual error: When the B-52 is flying low over Russia, the shadow on the ground is a Boeing B-17G, a World War II propeller driven bomber.
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)
Continuity mistake: Throughout the movie the outside shots of the B 52 show a shadow on the ground. That shadow isn't of a B 52 jet bomber but that of a B 17 WWII prop. It isn't a B 29 either, for the cord of the B 29 wing is thinner than a B 17s; Also, the wings and fuselage are much longer. The most obvious clue is the shape of the B-17 vertical tail- it is unique to the B-17, and much different from that of the B-29.
Continuity mistake: In the first War Room scene, when George C. Scott outlines the situation and his "six points," the folders in front of him move around; they're in a different position in each angle.
Continuity mistake: When Mandrake and Ripper are in the latter's office and he is firing out of the window, Mandrake holds a chair in front of him for protection. In the next shot from behind them, the chair is nowhere near him. (00:52:10)
Continuity mistake: Just before Ripper kills himself, the cigar's shadow across his face indicates bright lights at the back of his office, away from the windows. When Ripper and Mandrake are seen standing together, bright lights are coming from the other direction. The direction of the shadows alternates between the close-ups and the wide shots.
Continuity mistake: During Dr. Strangelove's last delivery in the war room the Russian ambassador is standing next to his wheelchair, looking straight and grim. Strangelove develops some rather macho ideas about the ratio of women and men in the mine shafts after, and the ambassador turns to him and says with a smile, "You have an astonishingly good idea." but when the camera angle changes he is looking as straight and grim as before. (01:27:55)
Revealing mistake: In the sequences where Mandrake and Ripper are under attack by the US Army, we see exterior battle sequences in front of the base. However, no matter how many bullets are fired at the building, all the windows remain intact.
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)
Factual error: After the B-52 has been hit by the missile it's supposed to leak fuel at a rather high rate. Such a leak would cause a visible trail, however, we only see some black smoke right after the hit which disappears after the fires are extinguished. (01:01:55)
Revealing mistake: Matte lines are visible on Major Kong as he falls through the bomb doors.
Factual error: When Major Kong is riding the bomb down like a horse, there is absolutely no wind whatsoever. Not only do we not hear it, but we can also not see any wind effects on Major Kong, as he can be heard to yell and holler quite clearly, and he is waving his hat like there is no danger of it blowing out of his hand.
Factual error: In the scene outside the where they U.S. Army soldiers are attacking the Generals headquarters, you see one American soldier firing at the headquarters building using a WWII era German Army MP40 Schmeisser submachine gun. Although not uncommon for American solders during WWII to use captured enemy weapons in a tight situation, it certainly would not be issued or allowed in the stateside peacetime early 1960's. Several soldiers are actually carrying and firing the U.S M3A1 "Grease Gun", but a few are doing the same with MP40s, presumably as a stand-in for the "Grease Gun".
Character mistake: The so-called cobalt chlorium (.) G, which is supposed to be used in the Russian doomsday device, has, according to the Russian ambassador (and Dr. Strangelove), a half-life period of 93 years. He then states that it would contaminate Earth for 93 years. However, per definition half of the radioactivity would still be left after this period. (00:47:30)
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.
Revealing mistake: A string is visible on the left wing of the bomber in one of the shots right before it drops the bomb.
Continuity mistake: While the crew is reviewing the attack profile James Earl Jones is shown reading the first page, then switching to the second page. A few seconds later he does the same thing again.
Visible crew/equipment: During the pre-bomb drop check near the end, there is an exterior shot of the plane. Look in the top-right quadrant of the screen, and you'll see the camera crew reflected in the window glass of the camera plane.
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.