When the U-boat sailors batten down the hatches on the SS Seaflower, a man is seen climbing up the ladder with a hat and scarf on. The film cuts away looking up the ladder and when it cuts back, the same man starts to climb the ladder again, this time without a hat.
The radio message showing that the SS Seaflower is sinking and mentioning that Lucy Armitage is aboard appears twice - on different forms and in different handwriting (despite being written by the same radio operator).
When the aircraft approaches the Deutschland, a magazine can be seen on the observer's machine gun. When they decide to attack, the observer is seen to attach a magazine to the gun that now does not have one.
The U37 Commander says to take the submarine down to 50 feet. Being German, he should have said 15 meters, as Germany used the metric system. The Officers on the Deutschland, later in the movie, use metric measurements.
Although the British Royal Navy introduced anti flash gear during the First World War, the Navy and Royal Marine gun crews do not don any protective equipment.
The Pocket Battleship Deutschland was renamed Lutzow in January 1940, seven months before the release of this film.
During the battle, John Laurie is a loader inside one of the turrets. He then appears on the bridge in a duffle coat to give a message to the Captain and seconds later he is back in the turret without the duffle coat.
When the order is given to 'Cease Fire', an officer speaks into the speaking tubes. However, these were put out of action earlier with orders being passed along a chain of men.