Revealing mistake: John Wayne suffers a broken arm and goes for a x-ray wearing a cast. At the bottom of the cast a slit is visible which allows the fake cast to be easily removed.
Revealing mistake: A the beginning of the attack on Pearl Harbor Destroyer 298 in the harbor. A shot of the ship shows an empty depth charge rack; a subsequent shot shows 1 charge on the rack, a tear shape type which was not introduced until later in the war. When the ship later attacks a Japanese sub the shot shows the old "ash can" charge being dropped.
Revealing mistake: During the attack on Pearl Harbor, we see a sailor cut the stern line so the destroyer can get underway. But the bow line is still attached as the ship is supposedly moving off.
Answer: One Star rank wasn't formalized until 1943. Rear Admiral lower and upper wore the same 2-stars.