When Robert Ryan's character rides up to the shipwreck on the beach, his foul weather jacket has a US Navy emblem on the left breast. He's in the Coast Guard, not the Navy. After he dismounts, the emblem is gone.
Early in the film, Scott has a nightmare about the sinking of his ship by a mine. Before it strikes the mine, the ship has two wide funnels. While plunging underwater towards the seabed, it has three narrow funnels.
Peggy says her husband's "optic nerve was cut," which is why he's blind. But, although she refers to the optic nerve in the singular, people have two optic nerves - one for each eye.
Toward the end of the movie, Peggy is talking to Otto on the phone to warn about her husband and the Lt. It is the same phone they are each talking on.