Continuity mistake: In a scene supposed to be after the ship has been fitted with radar, it is shown entering harbour with the 'lantern' removed and the aerial covered, which is how it's shown before the ship has the radar fitted.
The Cruel Sea (1953)
1 continuity mistake
Directed by: Charles Frend
Starring: Denholm Elliott, Jack Hawkins, Donald Sinden, John Stratton
Other mistake: One of the depth charges used to try and sink a German submarine is clearly marked "inert filling" so it would not explode.
Tallow: If anyone else makes a noise, I'll have his guts for a necktie.