Plot hole: The huge guns are set high up on a cliff face facing out to sea and it is obvious that they cannot be depressed to fire at a downward angle - the massive gun carriages set on rails would prevent that happening. They cannot be elevated to fire at an upward angle, too, because they fit pretty snugly in the hole cut into the cliff face to accommodate them. This means that their maximum and minimum ranges would be quite close together, covering a strip of maybe a few hundred metres either side. Given that the sea is completely open on the side of the island they are protecting, why don't the ships targeted by the guns while passing the island simply sail inside or outside of the narrow stretch of sea the guns can hit?
Factual error: During the train ride scene, the train is being pulled by a modern Yugoslav railways electric locomotive, despite that it was manufactured postwar and that there were no electrified rail lines in 1940s Yugoslavia.
Factual error: During the last stand-off between Spyros and the German officer, the latter is wielding a Sten gun. Even though the Germans did capture many Stens, they were just put in storage (until after Stalingrad) since they were deemed "too primitive." So no way for that officer to get his hands on a Sten, and why would he use it in preference to a brand-new, shiny MP 40 anyway?
Continuity mistake: When Col. Stavros rips open the back of Anna's blouse to reveal whether there are scars, the closeup shows Stavro's German uniform with ribbons on his left chest. When the camera cuts to the next frame, the ribbons have vanished.
Continuity mistake: After escaping from the Germans, when they left Franklin in their care, they are driving in a truck. Looking at them, L to R, Stavros, Mallory and Brown, driving. A few seconds later, Maria is driving and Brown not seen, probably in the back. Later, when they take over the armored car, after killing the Germans and pushing their own truck over the cliff, they drive off in the same direction that they just came from.
Factual error: Captain Sessler, the SS officer who questions the commando team, has no SS sleeve eagle on his tunic. Also, the eagle on his cap is the Heer (regular army) style rather than the regulation SS style.
Other mistake: When Spyros has his last stand-off, he fires his Sten gun at a number of German soldiers and one officer. But even though Spyros only fires forward and does not sweep his gun, every German soldier in his line of fire dies, and the officer remains miraculously unharmed. (02:16:23)
Character mistake: In the movie, Gregory Peck claims that he speaks German "perfectly." But in the scene where he uses the dead cliff guard's radio, he speaks with a noticeably thick - and highly un-German - accent. (00:57:22)
Suggested correction: The guns are firing across a strait. A strait is a "narrow passage." Since the targets must appear at a limited range, the guns only need a limited elevation angle.
Noman ★
Watch the film again. The guns are facing the open sea. There is no land visible anywhere behind the ships. If that's a strait, it's a very, very wide one.
The mission given says the guns are guarding a strait. The last shot of the six destroyers shows land behind them on the opposite side of the strait.
Noman ★
Other summaries explain that the strait is only deep enough for the ships at the place which matches the guns' range. So ships could not take advantage of further away or closer in.
Then what are the dark shapes rising out of the sea on the far side of the ships. If they are not islands, what are they?
Noman ★
Suggested correction: That the gun carriages are supposedly set on rails is not correct. In the novel template, as well as in the film, it is shown that the guns were installed on turntables. And as for their variable angles of fire - it could be due to (fictional) modifications.
Daniel4646