Starring Ben Stiller, Jack Black, Robert Downey Jr., Nick Nolte, Brandon Jackson, Steve Coogan, Danny McBride, Bill Hader, Jay Baruchel, Reggie Lee, Matthew McConaughey and Tom Cruise This film is a DreamWorks Pictures release and is rated PG-13 for pervasive language including sexual references, violent content and drug material. It runs 106 minutes. `Thunder' seamlessly blends comedy and action By CHRISTY LEMIRE AP Movie Critic "Tropic Thunder," Ben Stiller's extravaganza of a Hollywood satire, couldn't be any more "inside-baseball" if it contained references to the infield fly rule and Rule 5 draft picks. This movie-within-a-movie is certainly his most ambitious production as a director and it contains some of the biggest belly laughs of his career. But while it blends comedy and action sequences far more skillfully and seamlessly than this summer's "Pineapple Express," which shifted from one genre to the other, the endeavor winds up feeling overwrought and repetitive. Stiller produced, co-wrote the script and stars as Tugg Speedman, an increasingly irrelevant action hero who now leads the ensemble cast of the Vietnam War epic "Tropic Thunder." Tugg's previous attempt at being taken seriously, the critical disaster "Simple Jack," found him playing a slowwitted farm hand; "Tropic Thunder" may be his last shot at redemption. When Tugg and his equally pampered cast mates turn out to be too distracted to commit to the production, and costs start spiraling out of control, the overwhelmed first-time director (Steve Coogan) leads them into the jungle to bond and fend for themselves. But what they think is a carefully crafted exercise in make-believe turns out to be all too real when they run into a heroin manufacturing operation led by a cigar-chomping, preadolescent drug lord (Brandon Soo Hoo, who's fierce at just 12). Jack Black is typically manic and a bit one-note as Jeff Portnoy, the drug-addicted comic star of the flatulent "Fatties" franchise. (Think "Klumps," only more obnoxious, if that's possible.) But it's Robert Downey Jr. who takes the humor to a daring, inspired level with his hilarious turn as Kirk Lazarus, an Academy Award-winning Australian actor who's so method-y, he undergoes skin-pigmentation surgery to play a black soldier. While this probably sounds tasteless and potentially offensive, a couple of factors make it work. First, of course, there's Downey himself, who's intelligent enough to bring nuanced bravado and even some surprising sympathy to the role. (He also delivers the film's funniest and most insightful speech about the strategy it takes to play mentally impaired characters.) And considering Downey's propensity for digging deep for his own roles, including his Oscar-nominated performance in "Chaplin," it's a cute, sly in-joke to have him poke fun at himself in this regard. Second, there's Brandon T. Jackson as rapper-turned-actor Alpa Chino (say the name out loud to yourself), who is black and who calls Kirk out for the ridiculousness of co-opting his culture.They all end up trekking through the marshy wild together, bickering and steadily unraveling, along with scrawny first-timer Kevin Sandusky (Jay Baruchel), who's just happy to have a gig. Nick Nolte is a perfect casting choice to play the grizzled vet whose rescue memoir is the basis for "Tropic Thunder," with Danny McBride getting some goofy laughs as the film's mulleted explosives expert. Meanwhile, back in Los Angeles, studio chief Lee Grossman (Ton Cruise) barks orders and gets off on the power he wields even in this time of crisis. Cruise's supporting performance has its wondrously freaky moments, but it's not nearly as hysterical (or career-altering) as the early hype would suggest. Hollywood insiders will scream in recognition at this portly, profane volcano of a man, but mainstream audiences will probably just chuckle here and there -- and that's true of many of the gags in "Tropic Thunder." The screenplay from Stiller, Justin Theroux and Etan Cohen doesn't have anything particularly original to say about the insanity of Hollywood excess -- Matthew McConaughey, for example, is appropriately slick as Tugg's agent, whose primary goal is ensuring that his client has TiVo while on location -- but the film makes its points mostly in a vivid, lively way. That is, until the explosions and other knowingly over-the-top moments of violence grow redundant. As in his 2001 fashion parody "Zoolander," Stiller's direction is too straightforward to engage us on anything but a superficial level. Having said that, make sure you arrive at the theater on time for "Tropic Thunder." The fake trailers at the start might just be the best part of the trip.