Make that a ton of fun. “Birdman” is a complete blast from start to finish. The gimmick here–and it’s a doozy, and it works beautifully–is that Inarritu has created the sensation that you are watching a two-hour film shot all in one take. Working with the brilliant and inventive cinematographer Emmanuel Lubezki (who won an Oscar this year for shooting “Gravity” for Inarritu’s close friend and fellow Mexican director Alfonso Cuaron), Inarritu has constructed the most delicate and dazzling high-wire act. And indeed, before shooting began, the director sent his cast a photo of Philippe Petit walking a tightrope between the World Trade Center towers as inspiration.