Continuity mistake: After Smith and Schaeffer are done rigging the trees and poles with explosives, Schaeffer gets off the motorcycle and you can see the seat of his pants is wet. As they are entering the shed, the seat of his pants is now dry.
Continuity mistake: When Smith and Schaffer intrude on Carnaby's interrogation, the Gestapo officer and Mary are having drinks in the café, where he makes a statement that might reveal a fault in her identity (a location in Dusseldorf). Her hand is fixed on her chin, but the next cut shows her hand fully on her cheek.
Continuity mistake: Major Smith (Richard Burton) forces one of the traitors out of the castle window on a rope. He is wearing standard battle dress. When the traitor is shot by one of the Germans, he falls wearing a camouflage smock.
Continuity mistake: In the scene where the group parachutes in, the sky is cloudy and we can see snowfall, but watch carefully, as the men make their way to the equipment containers and then to find Sgt Harod we constantly see shots switching between cloudy and snowfall, then to no snowfall and sometimes sunlight, then back to cloudy and snowfall again. This switch back and forth is even more evident on the closeups of Richard Burton.
Continuity mistake: In the scene where they all jump from the sky tram into the water after escaping from the castle, we see the blonde woman (Mary) swim to shore. As she gets out, her hair is absolutely soaked and matted to her head. When the angle of the camera changes, we see her only this time, he hair is almost perfect and only slightly damp and is actually blowing in the soft breeze.
Continuity mistake: When Burton and the others go up the wooden staircase to approach the radio room, an upright beam is already charred by fire, but this wood only catches fire later when Eastwood throws the first grenade back at the Germans.
Continuity mistake: When Burton kicks Donald Houston off the cable car, they have been fighting on the side of the cable car. However, the next shot of Houston falling shows him falling from the front of it.
Continuity mistake: After looking at the Castle, Smith sends Shaffer back to the others to tell them to stay behind the tree line and he goes to the radio to contact London. When he turns to go to the radio his MP40 has the butt extended, but when he gets to the radio it's folded back again.
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.
Continuity mistake: The stub of the tree which is cut down by an explosion during the bus escape is very even and clearly cut with a saw.
Continuity mistake: When Eastwood is looking through binoculars at the cable car going up to the castle (the studio model), Burton arrives down the hill and lies beside him and there is no cable car to be seen at the actual castle in the background.
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.
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.
Continuity mistake: At the parachute drop the close-ups of Smith shows his face in sunlight, but the wider shots are grey and foggy.
Continuity mistake: When Eastwood gets off the German motorbike after the escape from the town, the seat of his trousers are wet but 2 seconds later are bone dry.
Continuity mistake: When the Germans set up the machine gun in the corridor and are shot by Eastwood, they collapse next to and over the machine gun in the middle of the corridor. When the team escapes down the corridor later the gun and the bodies have disappeared.
Answer: When the guard comes in, Burton explains what's going on. Also he is dressed as a German officer so his explanation and actions are plausible.