Backed by the Pentagon: Averted; they thought the plot was ridiculous and refused to support the film. Instead, they were Backed By The Israelis.
Company Hop: All four movies are produced by different companies (and the second one is a Canadian-Israeli coproduction).
Dawson Casting: Late teen Doug is played by 20-year-old Jason Gedrick. But Aces: Iron Eagle III inverts this drastically by casting several actors who are way too young to be believable as World War II veterans (see What The Hell, Casting Agency? in the YMMV section).