The song that Marco (Porco) is listening to on the radio in the beginning is "Le Temps des cerises" ("Sakuranbo no Minoru Koro" in the original soundtrack), which is the song Gina will sing in a later scene.
The flying boats in Porco's World War I flashback story, are based on historical airplanes. Porco and his squadron are flying the Macchi M.5, an Italian single-seat fighter flying boat designed and built by Macchi-Nieuport at Varese. It was extremely maneuverable and agile, and matched the land-based aircraft it had to fight. The Austro-Hungarians are flying the Hansa-Brandenburg CC, a single-seat wooden-hulled fighter flying-boat, named CC after Camillo Castiglioni, financial controller of the Brandenburg company.
Originally planned as a comical in-flight short film. Due to the beginning of the Yugoslav Wars, Studio Ghibli developed the film into a feature length movie with a serious tone, while retaining the humor of the manga it was based on.
Sections of the trailer and movie were screened for a multi-celebrity audience at the "Save the Rose Theatre" event. Also see Saving the Rose Theatre (1989). Location of Shakespeare's theatre on the Southbank of London, was approved for museum status granted late in 1998.