Arguably the greatest movie musical ever made, Singin’ in the Rain is celebrated as much for its songs and dances as its behind-the-scenes lore: Gene Kelly’s 101-degree fever while filming the title number; Donald O’Connor taking to his bed with exhaustion after filming “Make ’Em Laugh”—only to have to reshoot it days later due to a camera malfunction; Debbie Reynolds rehearsing until her feet bled. But of all the “making of” stories, the most impressive is that Reynolds, only 19 at the time, learned to dance in just three months to play leading lady Kathy Selden.