Mattrac's plane switches between a Fortress I (small rudder) and a Fortress II (large rudder).
When the ship's lookout calls out to the bridge, there are two officers stationed two window panels apart. On the next cut, which is a long shot of the bridge, the officers are stationed just one window panel apart.
When planes are returning from the bombing run and approaching the house, the bomb bay doors are open. After this, when Jean is alerted, then the pilot orders the bomb bay doors to be opened.
When the German plane attacks the ship, the ship is shrouded in fog in the shots taken on the deck of the ship but there is no fog in the shots taken from the plane's perspective.
During bombing runs, the plane is being attacked by anti-aircraft artillery and fighters at the same time. This would not happen as the fighters would stay outside the area when AAA is firing on the planes to avoid being shot down by their own guns.
In the film, the aircraft used by the Free French squadrons are American-built Boeing B-17 Flying Fortresses and are described as such by Capt. Freycinet. There actually were two Free French heavy bomber squadrons based in England: Groupes de Bombardment GB II/23 "Guyenne" and GB I/25 "Tunisie", which were part of the Royal Air Force as 346 and 347 Squadrons, respectively. However, they did not fly Fortresses. Their aircraft was the British-built Handley Page Halifax. Obviously, for Hollywood purposes, Fortresses were easier to obtain than Halifaxes.
While still out in front of its target, a low-flying plane drops bombs that hit beside the boat and in front of the plane that dropped them.
The German aircraft attacking the freighter is correct for the period with one exception. The interior views of the air gunners show them using the wrong weapons. A 20 mm MG (machine gun) on a swivel mount is in the forward part of the gondola. In the rear part of the gondola, a 13 mm MG is mounted. The weapons shown are U.S. 50 cal MGs.
When Paula Matrac is in the marketplace, she notices a headline in the La Voix De Paris French newspaper about her husband Jean. The headline is in English, but the rest of the article, as well as all the other articles in the newspaper, is in French.
When the guns are fired from the plane, no ammunition moves through the gun. Further, when the men are being questioned in the boat, the boat is shown swaying back and forth as if at sea, but the lamp in the cabin doesn't move at all. Ship lamps on all sailing vessels are made to swing to remain level while the boat rocks back and forth, so the lamps should be moving in the opposite direction of the ship.
When Mattrac is pointing his fifty cal. machine gun out the waist gun window, machine gun sounds are heard, but the gun is not firing. The 50 cal. M2 machine gun produces a great deal of vibration when it is being fired. The gun did not vibrate at all.
When Matrac is shooting at the German bomber from the deck of the ship, the magazine on top of the gun rotates as it should while dispensing ammo, and there is a visible muzzle flash. However, no spent shell casings are being ejected from the gun, nor is there any visible recoil while the weapon is being fired.
When the German plane is dropping bombs on the ship, the bombardier drops them, and they explode right next to the ship even though the bomber can be seen to not pass over the ship for several seconds after dropping the bombs.
During the funeral, it is mentioned that Matrac's son is 5 years old. Assuming he was born in 1940 (his father condemned in 1939 plus nine months of pregnancy), the movie depicts 1944 or 1945. By that time, France had been already freed.
When Paula mentions that Matrac had wanted to go to do stories in South America, Matrac agrees and mentions Guatamala and Peru. Guatamala is in Central America.