The head of the Royal Swedish Air Force, general Bengt Nordenskjöld, demanded several changes in the script if the Air Force was to participate. For example, there could be no fatal crashes and it was "unthinkable" that a Swedish Officer could fall in love with a simple shop-attendant. So, the girl in question had to work in a library instead.
In a scene a J29 goes off the runway after a landing. This was a real mishap when the film crew just filmed landings, and was incorporated in the film.
Near the end of the movie, the rear part of a J29 is seen burning after a crash-landing. This tail was from an aircraft that had been involved in a fatal accident at the airfield where most of the film was made.