The scenes where Rupert Everett slaps Colin Firth on his rear end and where Everett kisses Firth's cheek were ad-libbed. Writer and director Oliver Parker thought Firth's stunned reaction was so humorous, he decided to leave them in.
While Reese Witherspoon was learning her English accent for this movie, her husband, Ryan Phillippe was learning a Scottish accent for his role in Gosford Park (2001). The person who picked it up fastest? Their daughter Ava.
Dame Judi Dench and Anna Massey reprised their roles as Lady Bracknell and Miss Prism, respectively. They played them on the London stage twenty years earlier. Anna received an Olivier award for that performance in 1982.
The business with "Ernest's" bill at the Savoy and the money collectors coming to Jack's country home is taken from a scene cut from the play prior to its publication.