“Birdman” is now playing at Sundance Cinemas. R, 1:59, three and a half stars out of four.
What is “Birdman”? A Hollywood in-joke, an existential drama, a backstage face, a magical realist drama, and a work of technical virtuosity so dazzling that it can only mean to to dazzle. This is a nutty, chewy, wildly ambitious film that leaps tall buildings in a single take.