Wine snobs can be some of the most insufferable people out there. This is displayed perfectly in Alexander Payne’s 2004 dramedy Sideways, if not just through the movie’s most famous line. As delivered by depressed oenophile Miles (Paul Giamatti): “If anyone orders merlot, I’m leaving. I am not drinking any f*cking merlot!” And with that, sales of merlot dropped straight into the barrel.

That sounds like it could be a story tied to the film, sort of like the unfounded rumor that sales of undershirts plummeted because Clark Gable didn’t wear one in a movie. But this is absolutely true. In a new feature marking the 20th anniversary of Sideways, winemaker Doug Margerum remembered the ripple effect that line had, saying everybody started switching to pinot noir instead of merlot. “We were having a hard time selling pinot then, but after the film came out,...