Corrected entry: In the scene near the end in which Ensign Pulver reads a letter from a friend reporting the death of Mister Roberts, the friend writes that Roberts and another officer died during a kamikaze attack on their destroyer while drinking coffee in the wardroom. In real life, wouldn't the two have been at General Quarters during such an attack, not drinking coffee below decks?
Corrected entry: About half an hour into the movie, Pulver is on his knees going through Mr. Roberts's locker, looking for a shoebox. Dolan comes in with Mr. Roberts's letter and refers to him signing it with his John Henry, rather than John Hancock.
Correction: There's nothing wrong with what he says. A John Henry means the same thing. They're both a reference to a signature.
Correction: This comment supposes that the ship was AT General Quarters. It's entirely possible that the ship Mr. Roberts was killed on was simply sailing and the kamikaze plane came out of the sun such that no lookout would have spotted them in time to sound General Quarters. Not all kamikaze attacks happened during regular battles.