You know all that military action that goes on in a lot of Hollywood blockbuster films? Well, the U.S. government usually likes to get involved to help filmmakers more realistically portray it.

This was not the case with "Marvel's The Avengers." The U.S. Defense Department pulled out because they deemed the film too unrealistic.

Perhaps it was the aliens. Or maybe it was the superheroes.

[Related: 'Growing Pains' child star's 'Avengers' role]

Well, it was actually the ambiguity of secret military law-enforcement agency S.H.I.E.L.D., portrayed in the film, that did "Avengers" in.

From a recent Wired report:

"We couldn't reconcile the unreality of this international organization and our place in it," Phil Strub, the Defense Department's Hollywood liaison, tells Danger Room. "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.

(Not to deviate from the topic, but doesn't Strub have, like, the coolest job on the planet?)

[Related: 'Avengers' star Tom Hiddleston told Chris Hemsworth to really hit him]

One example of the U.S. military's lack of involvement in "Avengers" is the fact that a few of the military's latest stealth jets that appear in the film were actually added digitally by the studio -- they were not real jets provided by the Pentagon, Wired further reports.

The Pentagon has greenlit military involvement, providing drones and jets for films including "Iron Man," "Transformers," and "Eagle Eye." The secretary of the Navy even appears in the upcoming "Battleship," starring Rihanna and Taylor Kitsch, in theaters May 18th.

But wait.

Like "Avengers," "Battleship" also portrays an alien invasion. Isn't THAT unrealistic? (Maybe the Pentagon knows something we don't. *wink*)

Watch more from 'Marvel's The Avengers' (the first trailer flashes to multiple scenes depicting the U.S. military):

'The Avengers' Theatrical Trailer Clip: Interrogation Clip: Face Off Clip: Desperate