As Scott pointed out in his review, you need not fear that this week's Superhero Movie is another brainchild of Jason Friedberg and Aaron Seltzer, whose satanic perversions of the parody genre -- Date Movie, Epic Movie, Meet the Spartans -- have been terrorizing unsuspecting audiences every year since 2006. Superhero Movie was actually directed by Craig Mazin, a protégé of the Zucker-Abrahams-Zucker dream team responsible for Airplane! and The Naked Gun, and produced by David Zucker himself. But it, too, is plagued -- albeit to a much lesser degree -- by what's turning out to be the problem with the entire modern generation of spoofs going back to Scary Movie: relentless pop culture specificity.
The basest incarnations of this, of course, are the Friedberg-Seltzer monstrosities, which may be worthless as comedies but which could prove valuable to historians because they indicate precisely what dominated the American zeitgeist in the few months before their release. It's too generous to call these films' vulgar spasms "jokes," but to the extent that's what they are, they depend entirely on either audience members' awareness of US Weekly-type factoids such as Britney Spears' shaving her head or their recall of particular scenes and characters in recent box-office hits. That's not to say that these kinds of jokes can't be funny -- the problem with Friedberg and Seltzer, as others have pointed out, is that they think throwing something current on the screen ("Look, Paris Hilton!") constitutes humor. But they do limit comedies' universal appeal and staying power.
I can't emphasize enough that Superhero Movie is light-years beyond Date Movie, etc., in every possible way. Still, it winds up doing much the same thing. In a decade, how many people are going to understand a reference to "2 Girls, 1 Cup?" How many will remember the Tom Cruise scientology video that gets an extended parody treatment? Nearly every scene is taken directly from a recent comic-book film -- mostly Spider-Man, but also Batman Begins and X-Men -- but will viewers be able to recall those movies in that level of detail a few years from now?
This sort of ultra-referential humor can work -- and does a couple of times in Mazin's film -- but ultimately isn't (I don't think) as funny as a more general lampooning of movie conventions. Think about it: what are the funniest jokes in the entire Scary Movie franchise? My picks would be: a) the part when Carmen Electra, on the run from a psychotic slasher, grabs a banana from a table that also held a gun and a knife, and b) the weird moment in Scary Movie 3 when the Shyamalan-style spinning camera makes Charlie Sheen dizzy (a gag that's reused, by the way, in Superhero Movie). Neither required you to remember a specific scene or character, or, worse, some piece of celebrity gossip. You just had to know your movies.
These days, you can pop in Top Secret! or High Anxiety and watch them without missing a beat. Sure, there are some specific references, but they're either so famous that they can be considered general knowledge (e.g. Mel Brooks's skewering of the Vertigo dolly zoom in High Anxiety, 19 years later) or not dependent on your recognition of the source (e.g. all the elements that Airplane! borrows from Airport, Airport 1975 and Zero Hour!). Of course it's theoretically possible that there are tons of jokes in these movies that fly over my head every time and I simply don't notice, but somehow I doubt it. I watched Airplane! for the first time when I was about 14, not having seen the movies it references and with no knowledge of 1980 pop culture, and I laughed my ass off. If a 14-year old watches Superhero Movie in 2020, I suspect it will be mostly a dead zone.
The timeless comedy may not be dead, but the timeless parody seems to be. [EDIT: Or it would be if it weren't for Edgar Wright/Simon Pegg and Judd Apatow/Jake Kasdan, as commenters rightly point out.]
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