When Gen. Carnaby is being interrogated he states his name, rank and serial number. He prefixes his serial number with RA which stands for Regular Army. The Army did not start using this designation until after WWII. During the war his serial number as an officer would start with an O.
Over schnapps in the nightclub, Major von Hapen and Mary/Maria have a dispute over the location of the cathedral in Düsseldorf. While the city does have a large church (the collegiate church of Saint Lambert), it is not a cathedral, as Düsseldorf has never been a bishop's seat.
Throughout most of the film, Smith refers to Schaffer as "Lieutenant," using the British pronunciation "lef-tenant." But in the final scene in the airplane, he uses the American pronunciation "loo-tenant."
After the swim in the river all four heroes are soaking wet. Yet when they are in the plane, Major Smith produces an immaculately dry notebook with the incriminating evidence. No wet pages or blurred ink.
After Smith and Schaffer initially climb into the Schloss Adler, Schaffer puts on a cap and Smith doesn't have one as they walk out the door of a room and into a hall. Less than a minute later, both of them are walking down another hall, and Smith now has a hat similar to Schaffer's.
When Major Smith goes into the Bier Keller, he is wearing an officer's peaked cap. He takes it off and places it on the table and we never see it again. (Apparently, it was stolen from the set during the lunch break.)
Smith radios HQ and tells them he is..."effecting entry within the hour." At HQ, Smith's transmission of "Broadsword calling Danny boy" is heard at a significantly faster rate than Smith spoke it into his radio.
The scenes showing the escape out the window shows the stunt people rappelling normally with full rigging in the long shots, yet in the close up shots the actors are just holding onto the rope and they were not shown rigging the ropes for rappelling and did not show the use of any "D" rings or other rappelling gear.
When Mary is escaping the castle on a rope, through the window, she moves backwards down the window sill to the edge of the wall. Both her hands are in front of her, holding the rope. The next shot shows her (stunt double) abseiling down the rope with one hand behind her back (the correct way to do it, the back hand is used as a brake).
When Maj. Jonathan Smith is shot in the left hand closing a door behind him towards the final sequences of the film, he bandages the hand. This bandage and the blood on the bandage and his hand, disappears and reappears throughout the cable car scenes.
The group waits for a train to pass the railway station before entering the village. The sound effects suggest that the locomotive passed only seconds earlier, but there is no smoke or steam lingering in the air.
When Lt. Schaffer is sliding off the roof of the cable car hut, he holds on with his ice axe, buried broad end in the snow. But when Maj. Smith reaches to help, the axe is now buried with the pointed end down.
The common weapon in the movie was the MP40, a German submachine gun. Thee MP40 could fire 500 rounds a minute, and had a magazine capacity of about 40 rounds. In several places in the film, characters fire for extended periods, and yet no one ever has to reload.
When the traitor is shot while dangling from a rope outside the castle, the close-up shows him wearing a standard German field gray uniform. In the next shot, as he plummets to his death, he is wearing a camouflaged winter overcoat.
When Major Smith drives the captured German Alpine Post Bus toward the line of planes at Oberhausen Airfield, you can see that the horizontal stabilizer (small wing at the tail) of the first plane has already been destroyed, probably from a previous take.
As they are beginning to cross the bridge into the town a car comes down the road into town and the men all move to the right, except Christiansen who moves the left, to let it pass. In the next shot all of them are on the right as the car moves forward.
With the Germans approaching the wood shed, Major Smith sets trip wire explosives and tells Lt. Schaffer to go out the window. Lt. Schaffer opens the window and begins his exit by straddling the window sill. In the next shot he is seen with both knees on the sill and he is backing out the window.
When Smith and Shaeffer backup the Nazi car up to push it over the side, they are somehow backing over a "construction dirt" ramp that just sent the car airborne. Also, the car that goes into the ravine is a good bit older than the one Smith and Shaeffer push.
In the escape with the snow plower bus - Smith hits the wired poles to trigger the detonators attached to the tree and the telephone poles. As the Germans pass by you can clearly see that one of the poles hasn't been knocked over by Smith, it does however explode.
When they prepare to leap into the river, the cable car appears to be over the middle of the river, perhaps even a close to the far bank. But when they do leap, the first jumper lands close the near bank and the cable car moves over the river once again.
When the captured German Alpine Post Bus races throughout the airfield, Schaffer and Mary shoot several small jeeps which flip over. As they do, the rope that flipped them can be seen being pulled off screen.
The helicopter seen landing in the castle courtyard is a Bell model 47G, not built until well after the war. While the Germans had a small number of working helicopters during the war (none of which would have been readily available to the filmmakers), the Bell does not make a convincing stand-in for any of them.
At the beginning of the film, during the initial briefing for the mission, Clint Eastwood is wearing the same colored green necktie that the British are wearing. Members of the U.S. Army wore khaki ties during that period.
Everyone, Allied and Axis alike, refer to the German mountain troops as the "Alpenkorps" throughout the film. The Alpenkorps was a real unit, but it was disbanded at the end of WWI. The WWII incarnation was known as the Gebirgsjager, the designation it carries to this day.
When Colonel Kramer introduces Major Von Hapen to General Rosemeyer, he states that the Major is Gestapo. The Gestapo were secret police and came under the control of Himmler's SS. The black SS uniform was not worn by Gestapo agents and so Major Von Hapen would not be wearing an SS uniform - he'd be wearing civilian clothes (if he was even at the Schloss Adler, which is unlikely). Further, when General Rosemeyer states that he would prefer to keep the interrogation of General Carnaby a "strictly Army matter", he's already talking out of school - Colonel Kramer is in the Waffen-SS, not the Wermacht.
While the uniforms for the mission are quite accurate by Hollywood standards of the time, with the correct Edelweiss patches for mountain troops and rank insignia, the shoulder boards show the wrong color for Gebirgsjager (incorrectly called the Alpenkorps throughout the film), being the light meadow green of the Panzergrenadiers (motorized infantry) rather than the noticeably darker and bluer green of the mountain and ski troops.
After the pin was pulled on the German "potato masher" grenades there was, depending on the model, a 4 to 8 second delay before the grenade exploded. The grenades thrown in the castle delay as much as 12 seconds before exploding.
Early in the film, Christiansen makes reference to a "Pathfinder squadron... with ten-ton bombs". The film is set some time before late 1944 which is when bombs of this size were developed, and the first wasn't dropped until March 1945. Also, the role of Pathfinder squadrons was marking targets, and they wouldn't have carried the bombs themselves.
At the beginning of the movie Colonel Turner introduces Schaffer, saying something like, "Lt. Schaffer needs no introduction, you will all recognize his shoulder patches of the Rangers Division." There were no Ranger divisions, only battalions.
In the flashback scenes in British H.Q., Lieutenant Schaffer is incorrectly wearing his paratrooper's wings over the right breast pocket flap of his dress uniform coat. U.S. Army qualification badges are always worn over (or on) the LEFT breast pocket flap.
During the briefing, early in the movie, the team is told that General Carnaby had been on his way to meet with his Russian counterpart regarding D-Day plans and that the meeting place was to have been Crete. That would be impossible as Crete had been seized in a German airborne assault in the spring of 1941 and remained in German hands until the war ended. Moreover, the Western Allies would not share top secret operational plans with their Soviet Allies.
Apart from wearing a black Waffen-SS parade uniform, von Hapen's outfit has several other discrepancies, most notably a standard Nazi party armband (the one worn with the Waffen-SS parade uniform sported black stripes along the upper and lower edges), and a close combat clasp in gold above the left breast pocket, an award worn by soldiers with extensive front line experience, not the Gestapo.
The staff car in which Smith and Shaffer are being transported following their arrest has "WH" license plates, indicating a Wehrmacht (regular army) vehicle. However, since the troops who arrested them are Waffen-SS, the license plate should have the distinctive runic "SS" (the "twin lightning flashes").
Booby traps using wires are placed by the road used for the escape yet there is a substantial period between this point and the eventual escape using the bus. However, the trip wires are fastened to posts at the roadside, not all the way across the road, so any passing traffic would not rip through them before the escape. The bus then knocked over the posts during the escape, triggering the timer mechanisms.
While the presence of signs reading "Militärkommando Hohenwerfen" in the castle would, at first glance, appear to be an error caused by using the actual name of the shooting location Schloß Hohenwerfen (called "Schloß Adler" in the film), similar signs can be seen on other buildings. This indicates that "Hohenwerfen" does not refer to the castle, but to the administrative region (e.g. a municipality) that contains both the village of Werfen and the Schloß Adler.
It is assumed that in the cable car, Maj. Jonathan Smith screws the light bulbs in, not out, to extinguish them. However light bulbs in public transport stations and vehicles (such as an aerial tramway) have reversed threads to prevent passengers from stealing them for their home.
With the action in the latter half of the movie taking place more or less in real time, it is never explained from where the Junkers Ju52 operates, and how Colonel Turner could get on board on such short notice. The only country from which he could've flown is Switzerland, and somehow it seems unlikely that the Swiss authorities would've allowed British uniformed personnel operating in Switzerland, much less allowed operations from her territory.
Although several stylish call signs are used in the radio transmissions ("Broadsword", "Danny Boy", "Father McCree"), most of the other operatives and Colonel Turner, as well as the team's location, are referred to by name in open transmission.
In Europe most bus bodies are made from aluminum. During the chase sequence the Germans repeatedly spray the back of the bus with bullets, somehow the thin aluminum skin of the bus and the soft bus seat manage to protect the occupants.
The bus stops after the bridge so that it can be booby-trapped. Yet the entire road up to that point had been elaborately booby-trapped. They could have even just briefly stopped and dropped a couple bundles of dynamite in the middle of the bridge with a 15-second timer so that it blew the bridge as they drove away. It made no sense to stop and booby-trap the bridge during the getaway, as it cost them valuable getaway time. But it did add valuable tension to the getaway.
The plot revolves around the rescue of an ordinary GI impersonating a general officer. However, what ever happened to the pilot of the Mosquito he was flying in is never explained. Presumably, if Cartwright Jones was a 'second rate actor' and an Army private, he was not a pilot as well.
In the final scene where Colonel Turner is shown the note book with 'his' name in it. It simply Reads 'Colonel Turner'. Turner is a common name, and there were a lot of colonels in the Wartime British Army. Simply having Colonel Turner without a first name or unit was hardly conclusive proof.
When the Nazi car (after Smith and Shaeffer's arrest) is pushed into the ravine, it explodes without apparent reason before touching the ground. The same happens to the planes of the airfield being lightly hit on the tail by the German Alpine Post Bus.
When Schaeffer mows down the Nazis climbing the stairs towards the climax of their escape from the Schloss Adler, one of the soldiers that falls over the balustrade has somewhat suspect gray hair for a crack SS trooper.
When the metal canisters which landed by parachute at the beginning of the film are first seen, there is an obvious trail through the snow leading into the far trees, indicating the canisters were placed rather than parachuted into position.
Near the end of the corridor firefight, Schaffer retreats into the room and a German soldier throws a grenade through the door. In the widescreen version you can see the grenade strike the door frame and bounce back at the actor's feet, yet there is an explosion inside the room where the grenade would have landed. And grenades do not explode in a fireball as shown in this, (and other) movies.
In the cable-car fight scene, Christiansen fires the silenced pistol five times and then throws the gun on the cable-car floor after the bullets run out. The gun immediately bounces several times, even up to shoulder height, suggesting it is in fact a prop-gun made of rubber or some other material besides metal.
The goof items below may give away important plot points.
Both Turner and Smith discuss the scandal to MI6 should the scandal of his treason get out. However, in 1939 the Nazis exposed MI6's networks in Europe, and the Special Operations Executive took over its functions in wartime.
According to the ending, Maj. Smith (Richard Burton) seems to have known all along who the traitor was, and the entire mission was set up to expose him. In WWII, when spy networks could make or break the war, no agency went to so much trouble to get a confession. The traitor was simply taken out back and shot. If further proof were first needed, a simple trap such as feeding wrong info to the traitor would suffice for proof. Going to the trouble of sacrificing good agents to sneak into a heavily guarded castle and capturing the suspected traitor just wasn't an option.