TROPIC THUNDER

My favorite gag in "Tropic Thunder" comes just before "Tropic Thunder" itself, in a movie trailer touting a fake movie called "Satan's Alley." (That's an in-joke for all you "Staying Alive" freaks, "Satan's Alley" was the Broadway musical John Travolta cavorted in.) The pretend drama, a kind of "Brokeback Monk-Man," stars five-time Oscar winner Kirk Lazarus as a tormented 18th century Irish priest who has big love for a fellow Man of God. Robert Downey Jr. plays Lazarus, and the wordlessly soulful goo-goo eyes he gives fellow sinner Tobey Maguire sets a high comic bar for "Tropic Thunder" to beat.

It doesn't beat it, in fact. The first adjective that comes to mind regarding director and co-writer Ben Stiller's comedy is "massive." While the film is funny, too, its size and scale inform the joke half of the time and compete with it the other half. But its sharpest arrows take precise aim at a hornet's nest of Hollywood egos.

Stiller, Downey and Jack Black play the leading actors stuck in a quagmire of a Vietnam War film, "Tropic Thunder," based on the memoirs of "Four-Leaf" Tayback (Nick Nolte). The Vietnam veteran and the film's hapless director (Steve Coogan) decide to break loose and "go native," aided by the special-effects explosives expert (Danny McBride). For maximum realism they venture deep into the jungle. Then the local drug lords take notice of this apparent threat. The fake war movie becomes a real one, while back in Hollywood, studio chief Les Grossman (Tom Cruise, amusing in an uncredited supporting role and a good deal of artificial pudge) tries to work up some concern while openly relishing the danger, not to mention the potential box office.

Clueless, preening actors unaware of their situation: That's the idea here. The gore is played for queasy laughs, as is, dubiously, the running gag about a film Stiller's character is trying to put behind him, "Simple Jack," about a mentally challenged farmhand. (The film's "retard" references have led to a threatened boycott by various disabilities groups.)When the film works, it's less about strident outrageousness and more about wit, and finding the right way to twist the "Platoon" and "Apocalypse Now" cliches into pretzels. My second-favorite sight gag involves Stiller's action-hero character, Tugg Speedman, rescuing what he assumes will be a grateful war orphan. But the steadiest supplier of laughs is Downey, who's playing a Serious Actor maniacally committed to his craft. How committed? He undergoes a controversial skin treatment to render him African-American in appearance so he can play the black platoon sergeant, thereby relegating the cast's actual African-American (Brandon T. Jackson) to a secondary role. I think we can agree that blackface humor is dicey humor. For it to be humor at all is an accomplishment. Fresh off "Iron Man" and looking like Fred Williamson in his "Inglorious Bastards" heyday, burying a Russell Crowe dialect deep inside the character voice he's developed for badassss Sgt. Osiris, Downey makes the conceit work because he's constantly trying to make two portrayals work, in tandem.

In the end "Tropic Thunder" is an expensive goof about an expensive goof, and the results are very impressive and fancy-looking. (John Toll shot it, he was the director of photography on "The Thin Red Line," among other epics.) Too impressive, really, to fully unleash the humor in the situations. Here's the litmus test: If you smile at the wild-eyed pose Downey strikes in the poster for "Tropic Thunder," you'll probably get your nine bucks' worth.

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