- The Tone Rangers is the name of an actual a cappella group in Washington D.C.
- Jennifer Aniston's character Brooke gets a "Telly Savalas" wax job during the movie. In real life, Savalas was Aniston's godfather.
- In the opening scene at Wrigley Field, Jon Favreau makes a reference to going to "Wiener Circle" to have hot dogs after the game. Wiener Circle is a hot dog stand famous for the staff yelling and cursing at you when you order. If you do not return the favor, they do not take your order. Generally, though, this only happens late at night on the weekends.
- Vince Vaughn's parents have bit roles in the movie. His mother plays a tourist and his father plays Jennifer Aniston's dad
- The Old97's are performing their song 'Time Bomb' while Brooke is waiting for Gary at the concert. The Old97's also played the same song during the opening credits of another Vince Vaughn movie, Clay Pigeons (1998).
- The original ending didn't go down well with test audience, as Jennifer Aniston fans found it upsetting. As a result Universal Pictures had to re-shoot. According to the Chicago Tribune, the first ending made basically the same point in a slightly different way.
- In some scenes, Gary plays video games on his PlayStation 2. The list of games he plays includes Grand Theft Auto: San Andreas (2004) (VG), Fight Night Round 3 (2006) (VG) and likely the 2006 edition of Madden NFL 2006 (2005) (VG).
>>> WARNING: Here Be Spoilers <<<
Trivia items below here contain information that may give away important plot points. You may not want to read any further if you've not already seen this title.
- SPOILER: The original ending featuring Gary and Brooke running into each other at an art fair each dating someone that looked identical to the other (Brooke's date looked like Gary, and Gary's like Brooke) was scrapped when it tested poorly. A new ending was filmed with the same result but featured Gary and Brooke running into each other on the street alone. In both versions the two remained broken up.
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