Tropic Thunder (2008)

There is something a tad wrong about foible-filled Hollywood folks lampooning Hollywood folks' foibles. Moreover, co-writer/director Stiller first had the idea for this parody of Apocalypse Now-type filmmaking two decades ago — as he recalls in the minidoc ''Before the Thunder'' — and it would certainly have possessed more bite back in the era of Platoon and Hamburger Hill. But Tropic Thunder boasts so many terrific grotesques — from Downey's never-break-character thesp to Jack Black's junkie comedian to Tom Cruise's mercenary studio chief — that you ultimately forgive the film's smugness and lateness. The meta-fun continues on the other extras, with Downey doing commentary in character (well, technically, his character's character) and a fake Werner Herzog- esque making-of ''Rain of Madness.'' B+