A subplot of the film was inspired by an article in Time Magazine about David Phillips, a University of California civil engineer who stumbled upon a lucrative frequent-flyer promotion. By purchasing 12,150 cups of Healthy Choice pudding for just $3,000, he accumulated 1.25 million air-miles.
During the scene where Barry Egan (Adam Sandler) is at the supermarket looking for the cheapest Healthy Choice food item, he is being followed by an out-of-focus character in a red outfit. It's Lena Leonard (Emily Watson) before they've been introduced.
At one point in the film, Adam Sandler (Barry) is being followed by the Steadicam as he talks on the phone. During one take, the front of the camera accidentally bumped into a table and knocked the camera briefly, causing the shot to jump from Sandler to an image of an out-of-focus piece of the set and then quickly readjust. Paul Thomas Anderson loved the effect and wanted to do it again, so the crew did more takes and right at the same point in the dialogue, they smacked the front of the matte box on the camera to reproduce the effect.
Paul Thomas Anderson first announced that his follow-up to Magnolia (1999) would be an Adam Sandler comedy at a press conference at the Cannes Film Festival. The news was greeted with laughter by the assembled press. When "Punch-Drunk Love" eventually played at Cannes, Anderson won the Best Director award and was nominated for the festivals' top prize, the "Palme d'Or". Months later, Sandler was nominated for a Golden Globe in the "...Musical or Comedy" category.
During a promotional interview for Magnolia (1999), a British journalist asked writer and director Paul Thomas Anderson which actors he would like to work with in the future. Anderson replied that he would like to work with Adam Sandler and Daniel Day-Lewis. The journalist believed Anderson was joking, because the two actors are from such different backgrounds and have very different acting styles. However, Anderson's next two films did indeed feature these two actors in the lead roles (this film starring Sandler, and Il y aura du sang (2007) starring Day-Lewis, who later collaborated with Anderson on Le fil caché (2017)). As of 2021, Anderson is the only director to have worked with both actors.
Paul Thomas Anderson: [overstretched score] In the first part of the film, a long, dragging score is used for about ten minutes.
Paul Thomas Anderson: [iris in/out] After Barry Egan (Adam Sandler) and Lena Leonard (Emily Watson) have gotten together in Hawaii, there is a shot of them walking down a hallway, away from the camera. They hold hands, and the shot closes with an Iris Out, the circle going around their hands.