Wayne Morris became interested in flying during this production and qualified as a pilot. He joined the Navy during WWII, became a fighter ace, and was awarded four Distinguished Flying Crosses and two Air Medals in 57 combat missions.
Olivia de Havilland turned down the lead role in this film, resulting in her suspension by Warner Bros., according to a contemporary article in The Hollywood Reporter.
The airplane seen during the titles is a United Airlines Boeing 247. First flown in 1933, only 75 were built. Airlines found it uneconomical due to the limited number of passengers it could accommodate - normally only 10. Twenty seven saw service as C-73 transports during WWII with the USAAF.
The American Airlines Douglas DC-3/DST (Douglas Sleeper Transport) shown at the beginning of the film, registration NC16002 was built in 1936 and named Flagship Illinois (changed to Flagship Tennessee during filming). On December 28, 1948 it disappeared on a flight from San Juan, Puerto Rico to Miami, Florida with 29 passengers and 3 crew members.
The "Stratosphere" airplane in the film is a Lockheed 12A Electra Junior, registration NC17342. The "NC" part had been painted over and replaced by an "X" to indicate it was experimental for this film. It had appeared in many other films, including Rosalie (1937), Nick Carter, Master Detective (1939), Secret Service of the Air (1939), Mercy Plane (1939) and Murder Over New York (1940). This plane was built in 1936 and sold to a private company. It was subsequently used by the RCAF in WWII with registration CF-BRK (RCAF 7653). Returned to the USA in 1944, it's was last known to be flying with registration N505 for the Cape and Islands Flight Service in Massachusetts until 1965. A total of 130 were built from 1936 to 1941.