The year’s inevitable Woody Allen film, Magic in the Moonlight, has a clever premise, an agreeable cast, delectable ‘20s period recreations of faux “Oriental” magic shows and Côte d’Azur garden parties, and an ever-slackening pulse. It starts off with a flourish and winds up limp, like a rabbit pulled out of a hat that turns out to be dead.Having gotten away with his last, more difficult trick — remaking A Streetcar Named Desire, except with zero sympathy for the protagonist — Allen probably thought that this one would be a cinch to put over. His hero, played by Colin Firth, is a British magician named Stanley who performs in a bald cap and Fu Manchu mustache as “Wei Ling Soo” — and is instantly recognizable from his crisp, misanthropic attack as Professor Henry Higgins. His Colonel Pickering is a magician named Burkan (Simon McBurney) who invites him to the South...