One of my favorites! As I've noted before, one of the script writers was
Bogart Rogers, a bona fide Yank ace in the RAF, who flew SE5's in No. 32 Sqdn. He'd met James T.B. McCudden during training (and greatly admired him), and he'd obviously read McCudden's book. He managed to work both "Green tail" and "Voss" into the script...
One of the few classic 1930's WWI movies that features RFC two-seater operations, with the importance of recon photography mentioned. The two modified DH4's that were used in the flick were painted up in a bizarre camouflage color scheme, with an American-French style squadron insignia of a grim reaper (appropriate to the tone of the film, though).
Fredric March and his antagonistic observer, Cary Grant
The costumes and flying gear seem to be pretty accurate, though.
The script never really explains how three Americans came to be in the same RFC squadron, but that's OK.
There were some Tommy Morse scouts used as set dressing, and some of the flying footage was lifted from older films (as was often the case). The American ace Oliver "Boots" Le Boutillier ( of No. 209 Sqdn)was one of the movie pilots who flew for the film.