Stupidity: Major Franklin is struggling up the side of the cliff while the rest of the group are on top of the cliff checking their equipment, then he slips and slides down the cliff side, breaking his leg. After seeing this, the group members reach for a long length of rope that was used to bring up the other members and the supplies. The commandos could have used the rope to help Major Franklin climb up and prevent him from falling and injuring himself.
Stupidity: The rock climbing scene shows Gregory Peck hammering in metal spikes to the rock face, but then using them only as a foot or hand hold and making no attempt to attach his climbing rope. The point about having a rope is surely that if you lose your grip, you won't fall very far.
Stupidity: When Mallory decides to answer the phone on the cliff top he's warned there will be a code word or phrase. It seems to me that a better choice would be to not answer. Even though there would still be a patrol sent, isn't it more likely that a sentry had accidentally fallen off the cliff than unknown commandos climbing such a challenging face in such horrible weather?
Stupidity: Since the resistance fighters were already on the island, they could have just lowered a rope from the top of the cliff and "top roped" everyone up. No special climbing skills would then have been required.
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