When Franklin starts to edge his way up the "chimney" in the cliff, at the very top two small figures can be seen looking down at him - presumably Mallory and Miller. But at the start of Franklin's climb, all the men are busy securing their equipment, and it is not until several moments later that first Mallory, then Miller, go over to the cliff's edge to check on Franklin.
After the team has scaled the cliff the Germans respond to an alarm jumping on trucks and driving towards the mountain. When driving off the you can clearly see printed Dodge on the back latch of one truck. Germans did not drive Dodge trucks in the second world war.
In the opening sequence at the airfield, Mallory looks out toward smoke rising from a crashed plane. The film takes place in 1943, but on the right side of the shot a c.1960 pick-up truck is clearly visible.
When Anna regains consciousness at the ruins and sits up in fear, Maria grabs her and tells her, "They're friends - our friends." She then repeats the phrase "Our friends" in Greek, dubbed in on the soundtrack, while her lips clearly form the words "Our friends" in English.
The steering wheel on the second truck the saboteurs hijack and use throughout the remainder of the film, is on the right, indicating it is a British, not German, vehicle. But in the scene immediately following their taking the truck, as Maria, Mallory and Andrea watch the bombing of the nearby town from the truck's cab, the steering wheel is suddenly back on the left.
In the shot establishing the outdoor cafe, a waiter is seen serving two men at a table. This exact shot is used again later to establish that the action has returned here. Other shots a re-used as well.
When James Darren has his final showdown with the German officer, there is a brief shot of the officer walking towards Darren prior to either firing. In this scene the officer's uniform already shows the bullet wounds which he has yet to receive.
When the Mallory team arrives by boat at the British Army post at 1600 hours on the first day, Mallory clearly has his briefcase handcuffed to his right armed as it had been at the Middle East airfield office. A few minutes later, while walking around on the dock, waiting for Major Baker to arrive, the briefcase is clearly no longer on his right arm, but then reappears again on his right arm just a few seconds later.
When Miller goes to tell Mallory about Franklin's injuries, Pappadimos and Brown are seen in the background standing by the unconscious Franklin, and Pappadimos starts to turn to his left to go to pick up his rifle. But in the close-up, as Brown expands on Miller's description of Franklin's medical needs, Pappadimos is suddenly back standing next to Brown, then turns to his right to go retrieve his gun.
In the briefing about the mission, Mallory is seen examining a photograph of the cliff on Navarone. The shot looking at the photo shows him holding it in his left hand, with a magnifying glass in his right. But in the shot immediately following, of Mallory at the table, he is holding a cigarette, not the magnifying glass, in his right hand.
In the prologue, the guns are shown firing, and as they do large clouds of smoke are emitted all around the bases of the guns. But after a couple of seconds the smoke abruptly disappears and the area is clear again.
At the British Army base, when Franklin asks Pappadimos, "Do you have your silencer?" Pappadimos answers "Yes," and screws it onto the barrel of his gun. Yet he was shown doing that earlier, while the team was waiting for Major Baker at the pier.
A grenade is thrown from the fishing boat into the Nazi patrol boat while they are right next to each other. In the next shot, when the patrol boat blows up, it is shown from a greater distance, and the fishing boat is nowhere in evidence.
After the team has landed on Navarone and scaled the cliff there is a meeting that occurs between Gregory Peck and Stanley Baker regarding Baker's failure to kill one of the Germans that boarded the team's boat on their way to Navarone. Peck refers to Baker's failure as occurring "this afternoon" when, in fact, a night separates the encounter with the German patrol boat and the time of this discussion.
Mallory and Anna sit together when Mallory has taken the first watch. In the first closeup (from Mallory's side) she has no tears on her cheeks, but in the opposite shot (from Anna's side) there are tears on her cheeks.
When Mallory is dangling from the cliff, he is repeatedly shown using his left hand to hold on to Andrea. However, in a couple of long shots, Mallory is shown using his right hand to hold on to Andrea. It would have been impossible for Mallory to change hands without falling off the cliff.
Oberleutnant Muesel calls SS officer Sessler by the rank of "Hauptmann". This is a German Army rank, equal to Captain, but was not used by the SS. The equivalent SS rank was "Hauptsturmführer," or "head storm leader". Further, Sessler's collar insignia appears to have only two stripes below the three pips, which is correct for an SS Obersturmführer, which was one rank lower. The insignia for an SS Hauptsturmführer had four white stripes below the three pips.
When the Germans are searching the gun positions for explosives, German soldiers are using mine detection equipment and 'sweeping' the tracks leading up to the guns. This is a useless activity since the detection equipment is a metal detector and would give off a signal due to the steel rails.
In the opening moments, the guns of Navarone are shown firing interspersed with footage of ships sinking. One of the ships shown exploding is the British battleship HMS Barham, which was not hit by coastal artillery but was sunk after being torpedoed by a German U-boat.
Most of the light cargo/utility vehicles (including the one dropped off the cliff) are not German in origin. The majority of the vehicles appear to be Dodge T214 and T215 series vehicles, manufactured in the USA, and passed on to the Allies through the Lend-Lease act - but not the Germans.
The 6x6 armored cars which appear repeatedly throughout the movie are not German SDKfZ series vehicles, but rather, American Ford M8 'Greyhound' armored cars, which were used by the Allies, but not the Germans. In addition, the tanks featured in the film appear to be American M24 Chaffee light tanks, which not only weren't in service in Germany, but did not enter production until 1944.
In the fight scene where Pappadimos is shooting at a German officer, the officer is using a Sten SMG which is British made with the magazine on the left side. German MP_38/40 magazines were located on the bottom.
When the Germans cut through the door into the gun tunnel, they only cut one of the two doors. By cutting out the wheel that pushed the locking rods up and down into the locking receptacles, the locking rods are freed up so that one side can be opened. The top rod would naturally fall down and unlock, but the bottom rod would have to be pulled up out of its receptacle and held there while the door was being opened. However nobody is reaching through the hole to hold up that rod when the doors are opened (in reality the steel that was cut with the torch would be too hot for a while to do this, and they were in a great hurry to reach the guns before they were sabotaged). Furthermore, only one door was 'freed' yet both doors were opened at the same time, right after the wheel on the one door was cut out with a torch.
Starting about 1:00:10 into the film, the commandos encounter snow. The operation takes place in the Dodecanese Islands between September & November, 1943. It hardly snows at all in the Dodecanese Islands, let alone in Autumn.
When Mallory and Miller are sitting in the truck below the guns, they use a small flashlight to illuminate the map. As they move the flashlight across the map, the circle of light stops but the flashlight continues to move for a moment after the circle of light stops moving; Mallory quickly moves it back. This shows the flashlight is not the light source on the map.
At the start of the film, we see a plane coming in for a crash-landing on an air strip. As the plane heads in, we see another plane, which looks like a bomber, defying gravity and quite clearly suspending itself in mid air. A few moments later, as the plane lands, a second bomber is seen clearly suspended in mid-air.
When a German truck is driven to a spot where there is an ambush waiting, a grenade is thrown and the truck blows up. However, you can see the truck move slightly, where the film crew have moved the original truck, and then put in a dummy or mock-up truck which can be blown up.
After the boat sinks and the unit is stranded on the island, Mallory begins to climb the cliff face. As the camera pans to the top, we see stars in the night sky above, even though it is raining profusely.
When the saboteurs in the Greek fishing boat attack the Germans on the patrol boat, a hand grenade is thrown at the German boat at the beginning of the attack, and the camera angle switches to view the grenade coming at it. An explosion occurs before the grenade lands in the spot where the grenade is clearly about to land and you can still see the grenade in flight for a split second after the explosion.
When the German scout plane makes its final pass over the fishing boat, it's shown banking in toward the boat at a steep angle, low over the water, but in the very next shot it's flying straight and level directly over the boat, at a higher altitude and from a different direction.
When the German patrol boat first stops alongside the fishing boat, and its captain calls out, "Lower your sails," the incorrect shot has been edited in: the German is clearly not speaking, and Mallory, instead of facing him, is looking back toward the stern, which he did not do until a few moments later when he speaks to his own crew in Greek.
Although the scenes of the ascent of the cliff take place in a rainswept, cloudy night, the shot of the German soldier plummeting into the sea after being thrown off the cliff by Andrea shows the body falling in clear weather.
When the boat piloted by Maria is shown coming to pick up Mallory and Miller in the sea, the person seen operating the boat in the initial long shot is plainly not actress Irene Pappas, who played Maria.
When Miller is slapping the grease on the pole, his hands are covered with a very thick layer of it, but when he puts the rat on the cannon supposedly a few minutes later, his hands are completely clean. There was not time to clean his hands so thoroughly.