Joel and Ethan Coen make a welcome and long-awaited return to comedy with Hail, Caesar!, a slap-happy valentine to the Technicolor heyday of Hollywood that lands somewhere between the trippy brilliance of The Big Lebowski and the goofball parable of O Brother, Where Art Thou?. It is a lighthearted yarn that goes down easy like the old-fashioned popcorn pictures it so lovingly spoofs.