The B-17s during the WW2 bombing raid have 1942 camouflage and USAAF stars, yet the combat scene depicts them being attacked by Me163 rocket fighters, which were not used operationally until late 1944, and then in much smaller penny-packet formations, rather than the squadron strength suggested in the movie. Additionally, the Me 163s are clearly models, going far slower than in reality, and have prototype markings without authentic camouflage. But, so much for 1950s special effects.
McConnell's B-17 is attacked by what the crew and the mission debriefing officers refer to as "jets." However, the aircraft are clearly Me-163 "Komets", which were rocket-powered. It's possible that the crews confused the Me-163 with the Me-262, an actual German jet fighter that was present around the same time.
In the opening scenes when Pvt. McConnell is taking flying lessons, the hangar identifies the location as 'Fitchburg Airfield', and a vehicle on the ground holds a 'MASS' license plate, clearly placing the scene in Massachusetts. However, in aerial scenes thereafter, the aircraft is flying over large tracts of orange groves, and later, when McConnell is evading the military police in a hotrod he hitched a ride in, they pass down a long road lined with Eucalyptus trees. There aren't very many orange groves or Eucalyptus trees in Massachusetts, although there are in Southern California where the movie was filmed.
During the part of the movie in which McConnell is flying combat missions as a navigator in Europe, his plane is a B-17 Flying Fortress. The real Lt McConnell flew in B-24 Liberators. However, this mistake is understandable, since very few B-24s were still flyable at the time the movie was made, while many B-17s were still operational as rescue, training, and transport aircraft.
In the cockpit of McConnell's B-17, the pilot and copilot are very confined, with their shoulders almost touching. In a real B-17, there is much more room between the two positions. Obviously, either a different type of aircraft or a cockpit mock-up was used in these scenes.
When Pvt McConnell is flying with the instructor in the Cub, the sticks are at chest height - in a Cub, the sticks are about waist high or about a foot shorter than shown in the movie. Also, later when McConnell is flying the F86H just before his crash, the stick is again shown as much taller than in the actual airplane.
Sykes is wearing incorrect rank stripes. He is shown with the five stripes of a Sergeant First Class, but his stripes include the diamond of a First Sergeant. A sergeant with a diamond in the center, a Sergeant First Class, would wear a total of six stripes instead of five.
Original post: "Sykes incorrectly refers to 'Brooks General Hospital' in San Antonio. The hospital is actually named Brooke General." Actually, there were two similarly-named military hospitals in the San Antonio area which were frequently confused: The School of Aviation Medicine at Brooks Field (later Brooks Air Force Base) and Brooke Army Medical Center in Fort Sam Houston. As this is a film biography of an Army Air Force/ USAF aviator, the character was more likely referring to the hospital at Brooks Field/AFB.
When McConnell shoots down two MiGs (actually USAF F-84's) while flying cover for the rescue helicopters, the MiGs emit white smoke that is supposed to indicate that they have been hit by McConnell's machine guns. But the smoke can be seen to be coming from under-wing cannisters specifically designed by movie makers to simulate the results of battle damage.