'Barbie' director Greta Gerwig laughs uncontrollably watching Michael Cera on the set, as his character, Allan, reacts to Ken's blunder on the beach. In behind-the-scenes footage, Greta drops to the floor laughing from Michael's guttural scream while filming the scene where Ryan Gosling's character bounces off an ocean wave in Barbieland. 'Barbie' is available to watch on digital platforms now.