The 1910-era airplanes used in this movie were replicas built using the authentic materials of the originals, but with slightly more powerful engines. About twenty planes were built at a cost of about five thousand pounds sterling each.
Two of the replicas (the "1910 Bristol Boxkite" and the "1911 Roe IV Triplane") built for this movie still fly across the English countryside as both are preserved in the "Shuttleworth Collection" based at Old Warden, Bedfordshire, England.
The French entry in the race, flown by Pierre Dubois, is a replica of the "Demoiselle", designed by the Brazilian expatriate Alberto Santos Dumont, who had been believed by the French to be the first to fly a powered aircraft, until Wilbur and Orville Wright's demonstrations in 1908. The replica builders were faithful in constructing the Demoiselle, but no one could get it to leave the ground until it was discovered that Dumont had been a very small man who weighed only eighty-five pounds (thirty-eight and a half kilograms). Female pilot Joan Hughes was hired, and she successfully flew the plane throughout filming.
Most of the aerial scenes were filmed before ten a.m. each day when the air was least turbulent.
Michael Trubshawe's character's name is "Niven". Michael Trubshawe and David Niven were very close friends from when they served in the military garrison at Malta together, and David Niven would call uncredited characters in his movies "Trubshawe" - so this was Trubshawe's way of returning the compliment.