The black musician Dooley Wilson became an instant celebrity after appearing in Michael Curtiz's Casablanca; Wilson played Sam, the pianist-singer in Humphrey Bogart's cafe to whom Ingrid Bergman famously instructs: "Play it Sam. Play 'As Time Goes By.'"
Shortly after the film's release, Wilson was offered a contract to appear as a nightclub entertainer. He happily accepted. On opening night, however, the club's manager asked him why there was no piano onstage. The explanation? Wilson didn't know how to play the piano; he could only sing. The music in the film had been dubbed in.