Hook-handed Vietnam veteran Staff Sergeant John "Four Leaf" Tayback's memoir Tropic Thunder is being made into a film. With the exception of newcomer supporting actor Kevin Sandusky, the cast—fading action hero Tugg Speedman, overbearing five-time Academy Award-winning Australian method actor Kirk Lazarus, loudmouthed rapper Alpa Chino, and drug-addicted comedian Jeff Portnoy—all cause problems for the inexperienced director Damien Cockburn, who cannot control them, resulting in a million-dollar pyrotechnics scene being wasted. With the project months behind schedule, studio executive Les Grossman gives Damien an ultimatum: get the cast under control or the project will be cancelled.
On Four Leaf's advice, Damien drops the actors into the middle of the jungle, with hidden cameras and rigged special effects explosions to film "guerrilla-style". The actors have guns that fire blanks, along with a map and scene listing that will lead to a helicopter waiting at the end of the route. Unknown to the actors and production, the group have been dropped in the middle of the Golden Triangle, the home of the heroin-producing Flaming Dragon gang. Just as the group is about to set off, Damien inadvertently steps on an old land mine and is blown up, stunning the actors. Tugg, believing Damien faked his death to encourage the cast to give better performances, assures the others that Damien is alive, and that they are still shooting the film. Kirk is unconvinced but joins them in their trek through the jungle just to get out of the jungle.
When Four Leaf and pyrotechnics operator Cody Underwood try to locate the deceased director, they are captured by Flaming Dragon. Four Leaf is revealed to have hands; he confesses to Underwood that he actually served in the Coast Guard, has never left the United States, and that he wrote his "memoir" as a tribute. As the actors continue through the jungle, Kirk, who has become convinced that Tugg's ineptitude is putting them in jeopardy, and Kevin, the only actor who bothered to properly prepare for his role, discover that Tugg is leading them in the wrong direction. The resulting argument results in Kirk leading the rest of the cast back toward the resort they are staying at as an increasingly delirious Tugg is captured by Flaming Dragon. Taken to their base, Tugg believes it is a POW camp from the script. The gang discovers he is the star of their favorite film, the box-office bomb Simple Jack, and force him to reenact it several times a day, leading him to become brainwashed.
Meanwhile, in Los Angeles, Tugg's agent Rick 'Pecker' Peck confronts Les over an unfulfilled term in Tugg's contract that entitles him to a TiVo. Flaming Dragon calls during the discussion and demands a ransom for Tugg, but Les instead delivers a profanity-laden death threat. Les is uninterested in rescuing Tugg and is instead delighted at the prospect of a large insurance payout if Tugg dies. He attempts to convince Pecker to play along by promising a Gulfstream V jet and "lots of money".
Kirk, Alpa, Jeff, and Kevin discover Flaming Dragon's heroin factory. After witnessing Tugg being tortured, they plan a rescue attempt based on the film's script. Kirk impersonates a farmer towing a "captured" Jeff on the back of a water buffalo, distracting the armed guards so Alpa and Kevin can infiltrate and find the prisoners, but a combination of broken Mandarin Chinese and inconsistencies in his story sets off the gang's boss. The actors, knowing their cover has been blown, begin firing, fooling the gang members into surrender. Their control of the gang falls apart when Jeff grabs the leader and heads for the drugs, and the gang, realizing the guns fire blanks, recover their guns and fight back.
The four actors locate Four Leaf, Cody, and Tugg and cross a bridge rigged to explode to get to Underwood's helicopter. Tugg initially remains behind, believing Flaming Dragon to be his "family," but runs back screaming, chased by an angry horde. Four Leaf destroys the bridge, rescuing Tugg, but as the helicopter takes off, the gang boss fires an RPG at the helicopter. Rick unexpectedly stumbles out of the jungle and saves them by throwing a TiVo box into the path of the grenade. The crew return to Hollywood and footage from the hidden cameras is compiled into the feature film Tropic Blunder, which becomes a major critical and commercial success. The film wins Tugg his first Academy Award, which Kirk presents to him at the ceremony.
Ben Stiller as Tugg Speedman:
Jack Black as Jeff Portnoy:
Robert Downey Jr. as Kirk Lazarus:
Nick Nolte as Four Leaf Tayback:
Matthew McConaughey as Rick "The Pecker" Peck:
Steve Coogan as Damien Cockburn:
Jay Baruchel as Kevin Sandusky:
Danny McBride as Cody:
Brandon T. Jackson as Alpa Chino:
Bill Hader as Studio Executive Rob Slolom:
Brandon Soo Hoo as Tran:
Reggie Lee as Byong:
Trieu Tran as Tru:
Tom Cruise as Les Grossman:
Various actors and celebrities portray themselves, including Tobey Maguire, Tyra Banks, Maria Menounos, Martin Lawrence, The Mooney Suzuki, Jason Bateman, Lance Bass, Jennifer Love Hewitt, Alicia Silverstone, Christine Taylor, Mini Anden, Anthony Ruivivar, Yvette Nicole Brown, Rachel Avery, Sean Penn, and Jon Voight. Co-writer Justin Theroux appears in two brief roles as a UH-1 Huey gunner and the disc jockey from Zoolander (shown in a deleted scene).