Factual error: In the shot where the three officers ride the aircraft elevator from the hangar deck to the flight deck after arriving aboard the admiral's carrier, you can briefly see some of the aircraft parked on the hangar deck, and they are jet aircraft. The aircraft have pointed noses, no propellers, and the fuselage shape and markings are consistent with first generation Navy carrier jets. These types were not in service until the mid-50s (See "Bridges of Toko-Ri").
Continuity mistake: When John Mills is looking through the periscope whilst searching for the German battleship the side view shows him moving the periscope from right to left, but when it suddenly cuts to a shot of what he is actually seeing through it the periscope is strangely moving from left to right.
Continuity mistake: When Lou is finally convinced that he won't get hurt being the umpire in the "Hit The Umpire" game, he runs to take his place then stops in front of the batter. As Lou runs to take his place he isn't wearing a baseball cap, nor is he holding one in his hands, but in the next shot, when he gets hit in the head by the batter, one has mysteriously appeared on his head.
Continuity mistake: At the end of the movie, Jack parks the car in front of a palm tree and walks onto the beach. The shot changes while he stands there for a few minutes. As the shot changes back to show him walking off the beach, the car is no longer in front of the tree, nor does he drive by during the credits. I hope he enjoys his walk back to Miami.
Continuity mistake: Just after Knoll has been beaten up we see Elwood sitting next to him. As Elwood switches on the light, we see that the left side of Knoll's face is covered in blood. After Elwood applies the bandage, the blood on his face has changed with much less blood on the left side. The blood was never wiped off.
Plot hole: Alain joins the Legion, goes through extensive training and eventually gets his photograph taken. That's how Galgani recognises him and sends two men to kill him. They arrive with a platoon at the fort just after Alain, Mackintosh and Luther. The photograph would have taken a while to get back to France and then the two men would have to go through the same training. So how do they both end up in the same fortress after they joined the legion long after Alain?
Continuity mistake: When Woody has the landing gear lowered on the burning airliner, only the right main gear comes down. When Pappy warns him that the other gear isn't down, he pulls up and goes around. As the camera pans over the plane, it shows the left gear down, and the right up. Then when Woody retracts the gear, once again the right one is down.
Revealing mistake: When the mayor's wife attempts suicide by stuffing herself with pills, she is lying behind a sofa, only her arm and the pill bottle being visible as she pours the contents into her mouth. In the next shot (a close-up), however, the crown of her head is visible, and it is evident that she pours the pills over the top of her head.
Factual error: Catus Decianus actually managed to escape from the massacre at Camulodunum and fled to Gaul.
Continuity mistake: When Harry's guide is captured by the British troops, they flog him. In the very next scene his back shows no evidence of him ever being whipped.
Other mistake: The exact same background shot of a Ventura bomber followed by two single-engine planes flying left to right is used three times during the film, twice at the beginning as they are planning the mission on the beach and then once at the end when the raid is over.
Factual error: Throughout the film the British infantry are armed with carbines. These were intended for issue to cavalry and are much shorter than the infantry issue Martini-Henry rifle.
Revealing mistake: During the Little Bighorn massacre one of Custer's lieutenants turns to address Custer and is struck in the back with an arrow, and the thick pad or board is visible under the actor's shirt.
Continuity mistake: When they are all lined up for their medical inspection at the beginning of the film, the sun is coming up behind the hut casting a shadow in the front. When the Sargeant Major is then shown shouting from the hut, "I want this one (Bartlet) scrubbed with a yard broom." You can now see by the shadows that the sun is shinning directly at the hut. This would be impossible as there is only a few seconds between shots for this change to happen.