Continuity mistake: When Mary Ure goes to secure the rope over the wooden beam to allow Smith and Schaffer to climb into the castle, she starts by hitting a narrow piece of wood which comes loose. The scene then momentarily cuts to the guys on the cable car. When it cuts back to Mary, the narrow piece of wood is back in place and she is knocking out the much wider piece next to it. (01:05:15)
Continuity mistake: When Schaffer climbs the rope into the castle, he reaches the top of the rope, grabs the window sill and starts to pull himself in. It then cuts to inside the room where Schaffer can be seen outside holding on to the top of the rope and then grabs the window sill to pull himself in, again.
Plot hole: When Smith and Schaffer are entering the castle via a rope Mary has lowered for them, Smith stops halfway up to look through a large window. Clearly visible through this window are the faces of at least two soldiers with others in the background. It is inconceivable that not one of them would notice: A) the rope suddenly dangling outside; B) Smith's solid frame as he stares in at them; C) Schaffer scrambling up the rope after Smith; or D) the rope bouncing around while Schaffer drags it in along with the attached backpack. (01:10:00)
Plot hole: In one scene, the heroes of the film (i.e. Burton, Eastwood and others) locked themselves up in the cable car control room within the castle. The pursuing Germans wasted valuable time trying to break down the heavy wooden door of the control room with axes. Why didn't the Germans use grenades or other explosives? They could have instantly blown open even the sturdiest wooden door.
Continuity mistake: During this sequence at the radio transmitter in Admiral Rolland's headquarters, whilst the Admiral is attempting to regain contact with Smith, Colonel Turner is seen in the background, smoking. At the beginning of the sequence, one shot shows him holding a cigarette between the fingers of his right hand. After a cut back to the Admiral, the next shot shows Turner holding the cigarette in the fingers of his left hand. (00:53:10)
Continuity mistake: As the stolen bus ploughs through the German airfield Smith yells to Schaffer, "Take out the control tower," so Schaffer and Mary point their guns high and start firing. There is a long shot of bullets strafing the control tower, glass shattering and the traffic controller falling backwards as he is hit. It is followed by a quick close-up of him in perfect health, shouting into his radio, then being mowed down by the stream of bullets. (02:20:00)
Continuity mistake: When Major Smith and the others have completed their parachute jump, they find Sgt. Harod dead in the snow. Major Smith says at first Harod broke his neck on landing, but later said to his trusted comrades Harod was murdered after landing. Since he was murdered by a member of the landing party there would be tell-tale footprints of the murderer in the virgin snow around Harod's body, but there are no footprints around him at all.
Character mistake: Before entering the tavern,Smith tells the team to meet outside in a 1/2 hour. When they are sitting at the table just before capture, he says he gave orders for nobody to leave.
Continuity mistake: In her castle room, Mary lays all the sticks of dynamite on their sides in the suitcase. When Smith opens the suitcase in the meeting room after they got the names of the spies, the dynamite is now standing on end.
Deliberate mistake: Smith and the team come down the mountain and into the village at dusk, yet it is light out during the entire movie.