Jimmy Fallon played a Disney Edition of “Box of Microphones” with Josh Gad on Tuesday’s The Tonight Show. They took turns singing random tunes while the microphones did strange and wonderful things with their voices. It ended, of course, with a duet singing of the title tune from Beauty and the Beast. Gad is among the actors making the late-night TV rounds this week in promotion of Disney’s live-action remake of its hit animated movie, opening this week.