A Night at the Opera (1935)

Their first film at MGM, and the most polished thing they ever made. Irving Thalberg signed the brothers once their Paramount contract ended, and many of the gags were tried out on stage before filming, so set pieces like the tiny ship's cabin that fills up with stowaways, maids and workmen land with near-perfect timing. The trade-off is the studio formula: a romance between a soprano and a chorus singer, played by Kitty Carlisle and Allan Jones, with musical numbers that slow things down. Newcomers who want a proper story with their chaos may even prefer it to Duck Soup. Watch it second either way.