During his audition, Thomas Haden Church stripped naked because that was what the scene called for. He later learned that he was the only actor to do that.
During an emotional scene in the film, Miles talks with great passion about Pinot Noir. After the release of this movie, sales of Pinot Noir wines rose by more than 20 percent over the 2004-05 Christmas/New Year period, compared to the same period the previous year. A similar phenomenon was experienced in British wine outlets. Miles is deeply disparaging, in a different scene, about Merlot, and sales dropped after the film came out. Ironically, Miles's prized bottle of wine, a 1961 Château Cheval Blanc, is a blend of Merlot and Cabernet Franc, another grape Miles disparaged.
The food that Miles, Jack, and Miles' mother consume during the dinner at Miles' mother's house gave the three actors food poisoning.
Paul Giamatti admitted to faking every bit of wine knowledge, and not understanding why anybody would care about it. He also claims he was shocked that he was cast in a lead role and initially thought it was a practical joke.
The source novel by Rex Pickett remained unpublished until Alexander Payne bought the film rights. The novel was released a month before the film premiered.
Rex Pickett: (the source novel author) The golfer who actually hit the ball when Miles hits the ball back at the golfers behind them. He claims that Paul Giamatti's exceptionally poor golf form made it impossible for him to accomplish the shot.