It’s true, superhero movies are generally not known for their adherence to strict reality. No surprise there, though I’d say it could be argued that Marvel has actually done a passable job of finding real-world ways and reasons for its heroes to possibly exist (Thor obviously excluded).
But in an angle that I freely admit I would never have anticipated, when the Pentagon chose to withdraw its support for Marvel’s THE AVENGERS due to its “unreality” they were actually referring to SHIELD any not any of the super-powered beings found therein. “We couldn’t reconcile the unreality of this international organization and our place in it,” said Phil Straub, the Defense Department’s Hollywood liaison. “To whom did S.H.I.E.L.D. answer? Did we work for S.H.I.E.L.D.? We hit that roadblock and decided we couldn’t do anything with the film.”
As an example: while the humvees which show up at the end (driven by members of the National Guard) were used in cooperation with the Defense Department, any of the military planes seen on or around the Helicarrier (“F-22 Raptors and what looked like F-35 Joint Strike Fighters”) were all inserted digitally as the military refused to provide real ones.
To be fair, Marvel has been suitably murky as to just what SHIELD is in the world of the movies – not that they have to explain everything away by any means, but is it an American governmental agency that has authority over America’s military, or is it a more international organization created via a sort of ”United Nations Security Council resolution” uses American military equipment on loan? Without answers to these questions, all Straub could do was decide “It just got to the point where it didn’t make any sense.”