Either “Streets of Fire” or “Warriors” or “Escape from New York”. I would love to think that a post apocalyptic world sees our day as we see theirs. With “Streets of Fire”, there’s also music, and with “Warriors”, you get costume coordinated street gangs and the idea that coke bottles were musical instruments.
Heh. My BIL went to a Presbyterian seminary; one of his professors showed Life of Brian and said, “Just about anything you need to know about the origin of Western religions is in that movie.”
Don’t want too many different kinds of musicals, so I think I’ll go with The Untouchables.
I think “Escape From New York” should give the right idea about current New York(and U.S.) history. 
For dystopian purposes, maybe the Jackpoint snippets from Shadowrun sourcebooks? They look more or less like hardcopy of message board posts by mercenaries working as deniable assets for powerful corporations.
I assumed you were linking to this one.
In the “misconstrued religion” category, a copy of Neil Gaiman’s American Gods. And maybe a copy of Dawkins’ The God Delusion.
What about an issue of Thor?
The Areas of My Expertise, by John Hodgman, minus the first 19 pages where he reveals that the book is nothing but lies.
Or else just Hobo Matters.
There is no genius like sick and twisted genius. If you are ever in Portland, Oregon the microbrew is on me, dude.
I think as long as you stick with the basics - Cowboys vs Nazis - the details will work themselves out.
For period parody, how about a copy of MAD Magazine from the sixties or seventies.
So that people can get some idea what the legal system is like, what about, first of all, Law and Order:SVU (either that or Cop Rock), and secondly, one of those TV judge shows, like Judge Judy.
I think Judge Judy would give them a good idea of how our legal system works.
How about an episode of St. Elsewhere or Scrubs to show off our medical system?
Some random episodes of The Simpsons would be an excellent primer on American suburban life in the late 20th and early 21st centuries.
Sorry-already decided to use Married With Children.
Hairspray (the original non-musical film), Fast Times at Ridgmont High and almost the entire John Hughes oeuvre as examples of typical American high school life.
The movie The Firm for a highly realistic look at the American judicial system today. 
You need a good American President for the cowboys to act at the order of, somebody fictional like Captain America or Neil Armstrong.