Corrected entry: The aircraft used in the movie could not have made the journey in real life for several reasons, the most important of which is that they would have find somewhere to land and refuel about every 150 miles (every 2 hours of flying time at a speed of 75 mph).
Corrected entry: When Tom Selleck and Bess Armstrong are discussing the price of the trip, they settle on 60,000 pounds; however, after the first plane is destroyed, he tells her she will pay for this plane "over and above the hundred thousand."
Correction: It is made quite clear that she is discussing British pounds, and he American dollars. Earlier in the film they quibble about that.
Correction: The Stampe biplanes used in the film had a maximum speed of 188 kmh (116 mph) and a range of 420 kilometres (260 miles).