In the scenes where the pilot crashes into no-mans-land, the Germans soldiers are shown wearing spiked helmets. The Germans abandoned these helmets in favor of the familiar trench helmets in mid-1915. They would not have been in use during the time portrayed in this film.
In several scenes an N number is visible on the tail of the plane. This designates an airplane of United states origin, and was not used on civilian planes until 1919. They would not have been on military planes.
In the scene where Rawlings and Lucienne say their final good-byes and Lucienne is on the wagon riding away, an older man with a white beard passes Rawlings on his left and looks at him. When the movie cuts to a shot behind Rawlings, you can make out the same older man except he has not yet passed Rawlings.
When the German soldier is drinking outside Lucienne's farmhouse, his bottle in the long shots is a squat white one like those the soldiers find in the cupboard, while the bottle in close shots is a tapered cognac bottle.
Fokker DR-1 triplanes were never used in the great quantities seen in the film. The filmmakers used them because they were easily distinguished from the allied biplanes, and didn't want to leave viewers unsure as to who was on what side during these sequences.
The anti aircraft artillery shown in use by the Germans was not of any type used by any side in the First World War, nor was anti aircraft fire nearly as effective or accurate as shown. Were any of the portrayed shell bursts as close as they appeared in the film, they would have instantly destroyed the aircraft with the combination of the explosive power, fire, and shrapnel.
In one scene Cassidy is being chased by a German fighter plane. He pulls up on the stick and gains altitude and slows way down so the German plane flies past him under him. WWI fighter planes were incapable of doing such a maneuver, they simply could not go fast enough and would stall.
The hammers the pilots are given to correct machinegun jams look like finishing hammers for small nails. When WW I pilots did take hammers aloft, they were mallets with large, heavy heads to exert the necessary force on a stuck charging handle.
Both the Nieuport 17 and the Fokker DrI triplane were equipped with rotary engines. This meant that the cylinders were fixed to the propeller and actually rotated around a fixed central shaft. In several close-ups of the aircraft in flight, the engine cylinders are shown stationary. This would be how they should appear if they were the more modern radial engine instead of the older rotary engine.
WWI biplanes were not capable of the aerodynamic maneuvers shown in the movie. They would have stalled or crashed had they attempted those maneuvers in real life. The aerobatics shown would be tough even for modern fighter planes to accomplish.
The Neuport 17 had outstanding maneuverability, and an excellent rate of climb. Unfortunately, the narrow lower wing, marking it as a "sesquiplane" design with literally "one-and-a-half wings", was weak due to its single spar construction, and had a disconcerting tendency to disintegrate in sustained dives at high speed, therefore many of the maneuvers shown in the movie would have resulted in loss of the lower wing of the Neuport.
The movie takes place in late 1916 and early 1917. The Fokker Dr.I triplane didn't appear until September 1917. Likewise, the Bristol Fighter and SE5a weren't available until after the time period depicted in the movie. Also, the paint schemes shown on the Dr.I triplanes are wrong. The crosses weren't painted on the upper surfaces of the lower wing and the all-red paint scheme was only used on Manfred von Richtofen's (the Red Baron's) plane; however many of the planes in his unit were partly red. Correct German fighter planes for the time frame of the movie would have been the Albatros DI,DII,and DIII, and the Halberstadt DII.
The German column marching through the fields near Lucienne's
farm includes several tanks. The German Army built only a handful of tanks during the course of the war, the first time they were used in action was on the 21st March 1918. The majority of tanks used by the Germans during World War One were captured French and British ones.
In the opening series of scenes from a train station in Lincoln, Nebraska clearly show the name "Union Pacific". Union Pacific never served or went through Lincoln, Nebraska during World War One. In addition the locomotive, passenger car, and goods wagon are of British origin.
Aquitania, the ship Lowry takes to Europe, ceased North Atlantic passenger service upon the outbreak of war in August 1914. She was ordered into service with the Royal Navy, serving as an armed merchant, a troop ship (though not again on the North Atlantic run until 1918), and a hospital ship. She did not return to civilian passenger service until 1920.
When Cassidy is in a head-on attack against the black triplane during the Zeppelin battle he is firing both a Lewis, mounted on top of the top wing, and a Vickers machine gun. A real Lewis gun has a drum magazine which rotates as the gun fires and the bullets advance against an internal spiral guide. When Cassidy's Lewis fires the drum is motionless.
The German airship has the tactical sign "L 32". L 32 had been produced by "Luftschiffbau Zeppelin GmbH" with the internal number "LZ 74" (LZ for "Luftschiff Zeppelin" = Airship Zeppelin). The tactical sign beginning with "L" tells us, that it had been an airship from the German marine and not from the army. "L 32" was built on 4th of August 1916 and carried out one reconnaissance mission for a naval attack against Sunderland and three bombing missions against England. Only one and a half month later - on 24th of September, British fighters shot it down. So there was never a mission performed against Paris or even France!
Aircraft engines of this era leaked oil and the real reason for the scarf was to wipe the oil off the flyer's goggles, not to protect the neck when turning the head as said in the movie. When the pilots returned to base after a mission their faces in the areas not covered by the goggles should of been covered by oil and dirt.
When Blaine takes off after rescuing Lucienne from the German soldiers at her farmhouse two German soldiers run in front of the plane and start shooting at him while he is taking off. One soldier is kneeling and one is standing. Blaine shoots them with the machine gun on his plane. Both soldiers die, even though the bullets should be well over their head, coming from a machine gun mounted 7-8 feet off the ground, especially since one of the soldiers is kneeling. To shoot them with the machine gun, Blaine would have had to nose dive the plane into the dirt to get the proper angle of attack.
In many of the takes of the computer generated aircraft flying through thick smoke from the battlefield, the smoke is apparently not affected by the passing of the airplanes. Real airplanes flying through real smoke will leave a very visible turbulence behind.
The goof item below may give away important plot points.
When Rawlings performs a barrel roll over the Black Falcon's aircraft, streamers can be seen on Rawling's wings, but when he completes the maneuver the streamers are missing from all subsequent shots (they were not present in any previous shot in the final battle either.)