SCSimmons beat me to it. I was going to say that in-jokes of this type can be found in Shakespeare (references to political developments, other plays and playwrights, etc.), and go back to the Romans. Then he says Aristophanes, and of course he’s right.
If you want to draw conclusions about the prevalence of the modern phenomenon – i.e., that it doesn’t seem a single movie comes out without some kind of cross-referential nod – it seems you can advance two theories.
First, mass communication has become so prevalent that the creative people who produce our entertainment, in “writing what they know,” don’t know anything beyond the movies, television, music, etc., that everybody consumes. This kind of insular, incestuous recycling can be seen, for example, in the films of Devlin/Emmerich, whose Godzilla and The Patriot are really nothing more than pastiches of their respective genres, cobbled together from bits and pieces of their forerunners. The “pop-culture reference” approach simply makes the allusions obvious, instead of trying to pretend that the material doesn’t originate elsewhere.
The second of the theories recalls Marshal McLuhan, and is also predicated on the notion of mass communication becoming so ubiquitous. When it’s an inescapable aspect of our everyday life, the media itself becomes a topic for exploration, as opposed to the “software.” Movies start turning into examinations of the moviemaking form, as in the propaganda-turned-inside-out Fight Club. Again, pop-culture references are simply the most visible artifact of this, as we in the audience are rewarded for knowing as much about the media as possible.
That’s probably a topic for GD, but I thought it was worth mentioning as a partial explanation about why the pop-culture thing, while not a new development by any means, seems to have become so overwhelmingly common.
