The "Magic" Mustang makes another appearance, this time with two Mustangs on the same mission. They change model and color schemes throughout the first bombing mission and the later reconnaissance mission. This also includes one shot with Mustangs with postwar markings (red stripes on the white bars on either side of the white star national insignia and "U.S. Air Force" on the tail) and tailwheels locked in the down position which was a field modification in the 1950s due to mechanical issues.
Sandy finds a .50 caliber shell casing in the back of the B-17 that he says came from an American fighter plane. The casing would have been ejected outside of the fighter plane and into the slipstream when the round was fired. What he should have found was the actual .50 caliber bullet which looks completely different. There's no way the casing from the fighter could have turned up in the B-17. Since the B-17 was armed with the same .50 caliber machine guns as the P-51s and the gunners were exchanging fire with the German fighters as well, the floor of of the B-17 would have been littered with the same kind of brass cartridge casings, proving nothing.
Fighter Groups did NOT share bases with Bomber Groups in the USAAF and certainly not in the European Theater of Operations, and would not have mission briefs and mission debriefings at the same base.
Not for the first time, Col. Gallagher flies a photo reconnaissance mission in a P-51 Mustang. There were several dedicated photo reconnaissance units in the 8th Air Force and they would have flown the missions.
P-51D Mustangs left the factory with an internal fuel tank behind the pilot's seat, the radio on top of the fuel tank, and an armor plate with headrest bolted in place between them and the pilot's seat. (That fuel tank was a big part of the reason the Mustang could escort heavy bombers anywhere over Europe.) There were actually three real-life incidents in which a P-51 pilot landed in an open field in German-held territory to rescue a buddy who had bailed out, as Lieutenant Wilson does for Colonel Gallagher. But in every case, the two pilots had to sit on the single seat, one in the other's lap, as there was no empty space behind the pilot's seat as there was in the obviously modified civilian-owned Mustang used for this scene. It was a very cramped flight back to friendly territory in each of the real-life incidents.
After hearing that enemy fighters are a 4 o'clock, Wilson looks to his left. 4 o''clock would be over his right shoulder.