Factual error: As Oddball and his motley crew depart with the "purchased" Tiger, Moriarity is standing up in the hatch, fiddling with his cap. Since this is the driver's position, and very cramped, either he is straddling the driver's shoulders, or driving with his feet.
Suggested correction: The tanks used in the film are mocked up Russian T-34's (As mentioned in another mistake) which changes the proportions of the interior. Additionally, in regards to the "cramped" quarters; Tiger 1 tanks are actually quite infamously known by the soldiers that crewed them for having spacious driver, and assistant driver (Bow gunner) positions; with some crew even able to lie down inside of them.
Continuity mistake: While Big Joe is talking down to the Captain in the boat, Joe is blocking the stairs to the upper deck with his whole body. As the Captain moves up the stairs, Joe is off to the Captain's right. When the Captain emerges from the lower deck, Joe is dead center of the Captain and then moves out of the Captain's path. (00:12:00)
Suggested correction: Watch closely as the captain starts climbing the steps. Joe moves to the screen right ever so slightly but still covering most of the steps. When the shot changes to outside the boat, Joe is still slightly to the side of the steps with his arm across the rest. He then moves out of the way completely. No mistake here.
Other mistake: When Telly Savalas drives into the farmhouse he leaves the chaplain in the jeep which is approx. 50 feet from where Clint Eastwood and the rest of the soldiers are planning to steal the gold. For about five minutes they are arguing quite loudly about if it is a good idea and afterwards they then agree to the heist and they all crowd around the map and are extremely jubilant. Is the chaplain still sitting in the jeep listening to all this? We never see him again. (00:38:15)
Suggested correction: This isn't a mistake; at best it's an unresolved plot point. The chaplain became irrelevant to the plot at that point so their story line ended without explanation. If anything it makes it more realistic.
