Corrected entry: As they prepare to attack the convoy, the radar operator reports incoming enemy aircraft, but never does give a bearing to them. The lookouts are scanning all over the skies, instead of one watching the relevant quadrant. As much a stickler for procedure that the captain is, heads would roll.
Corrected entry: During the attack, when the torpedo circles back, the submarine is passing 100 feet. No torpedo would have a depth set that deep, yet along comes the torpedo which passes just above the sub. I can understand a gyro failure, but a depth setting failure at the same time is practically impossible..
Correction: The torpedo that doubled back was only thought to be their own. Later in the movie, the plot showed it was from a Japanese sub hunting U.S. subs so the torpedo would have been set to a depth to hunt them.
Correction: The SD radar used aboard U.S. submarines during World War II to detect aircraft could only determine the range to the contact; it couldn't give any bearing information.