- The Danza: Julia Roberts playing Julianne Potter.
- Dawson Casting: Kimmy was age 20 according to the script; Cameron Diaz was 25 years old by the end of filming.
- Focus Group Ending: The original ending was to have Julianne hooking up with a random guy at the wedding reception, which audiences complained was an Ass Pull happy ending, that made it look like Julianne was still being rewarded after all of her terrible behaviour. Audiences also wanted to see more of George, so instead the ending was changed so that George appears at the reception instead to comfort her.
- Missing Trailer Scene: There is different dialog for the ladies room scene. This version has more of a Was It All a Lie? tone.Kimmy: I trusted you! Just tell me why!Julianne: Why did you trust me?
- Playing Against Type: The movie starts out passing off Julia Roberts in her usual rom-com role...until it becomes clear later in the film that she's actually the Villain Protagonist. This sleight-of-hand is basically why the film works.
- What Could Have Been:
- Sarah Jessica Parker was offered the role of Julianne, but was busy with her upcoming starring role on Sex and the City.
- Russell Crowe auditioned for Michael and was initially director P.J. Hogan's first choice. But then Crowe did a table read with Julia Roberts where he read the lines in mono-tone and refused to make eye contact with Roberts. Suffice it to say, he didn't get the part.
- Matthew Perry was also considered for Michael, but he and Roberts had recently dated, and Hogan worried about the effect this might have on-set.
- Several actresses auditioned for Kimberley, including Drew Barrymore, Laura Dern, Calista Flockhart, and Reese Witherspoon. Roberts preferred Barrymore, but Hogan pushed for Cameron Diaz. Roberts agreed to Diaz on the condition that Hogan cast her good friend Dermot Mulroney for Michael.
Trivia / My Best Friend's Wedding