Thanks to Weaver's inspiration at http://beyondthesprues.com/Forum/index.php?topic=4030.45here is the alien explanation of WW2 victory: extra-terrestrial airships were launching airplanes like our ones:
the P-38EM Excursion Module (or LEM: Lightning Excursion Module) was a fake that never landed on the Moon in 1939 despite the film "proof"...
Gotta say that the Lightning III bears quite a strong resemblance to the Earth Defence Directorate Thunderfighter from the TV series "Buck Rogers in the 25th Century".
You are right: probably the P-38's canopy would explode long before reaching Mach 28