Continuity mistake: In the middle part of the film, as they look out across the field you can see the shadow of a aeroplane cross the field.
Continuity mistake: When Hugh O'Brian and Barbara Bouchet are driving up from the beach during the Japanese attack, they are in a Lincoln convertible. When the car explodes and goes over the cliff, it is either a Ford or Mercury convertible.
Continuity mistake: In the last scene, 2nd Lt. Blair is holding an army carbine on which the barrel is noticeably bent downward.
Continuity mistake: Near the beginning, Lt. Col. Daniel Kiley is in a scout plane and flies over Col. Martin Hessler, who is in a German staff car below. Kiley tells the pilot to "rev the engine" just above the car to entice Hessler to look up at them, so he can get a good photograph of his face. The plan works, and the ground level movie camera shows Hessler looking up. When the "photo from the air" is later developed, it shows Hessler looking up from the ground level camera's perspective, eyes focused about 30 degrees behind the airplane and giving a profile of Hessler.
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.
Continuity mistake: The city railroad scenes were filmed in Spain, and many of the forest railroad scenes were filmed in Finland; in both of those countries, most of the railroad track is broad gauge (the rails are more than 5 feet apart). The plains and mountains railroad scenes were largely shot in Canada, where the rails are "standard gauge": 4' 8 & 1/2" apart. The rails can be seen to jump between far apart and closer together more than once as the movie progresses.
Continuity mistake: James Garner figures out he's being duped, and tells Eva Marie Saint to run out of the room screaming to draw attention to herself. She does and there's a shot of her on the hospital lawn with staff all around her. The next shot is James Garner looking out the window to see what their reaction is, and Eva Marie Saint can be seen behind him in the room.
Continuity mistake: When the train is taking water it is sitting on a far right spur line, but when it leaves it is on the main line.
Continuity mistake: In the scene when Richard Harris and Kirk Douglas parachute back into Norway, there is a white parachute blowing in the wind. Kirk Douglas goes to collect it, but there are footprints already in the snow where they have previously filmed a retake. (00:27:00)