DVD: Tropic Thunder, Rental & Retail, (Paramount)

Ben Stiller, Robert Downey Jr and Jack Black star as three has-beens who think they're filming a Vietnam war epic in the jungle, unaware that the people who keep shooting at them aren't actors playing the Viet Cong, they're genuine trigger-happy guerrillas.

It's not a bad idea, and there are sporadic bursts of brilliance, but, like its heroes, it soon loses its way. For a comedy about a mega-budget Hollywood folly, it's awfully close to being a mega-budget Hollywood folly itself.