According to director Brett Ratner, during the scene at Grauman's where Detective Carter bribes Stucky for information, there was so much improvisation between Chris Tucker and John Hawkes that they almost didn't think they could edit it together as a coherent conversation. There are still continuity errors in the dialogue for this reason.
According to director Brett Ratner, this film is the first one released in the U.S. featuring Jackie Chan in an English-speaking role without any kind of dubbing. According to Ratner, before this film Chan always had his voice dubbed over in his English-speaking roles because of his uncertainty in speaking the language. For this film, however, Ratner convinced him to forgo the dubbing as it would lend to the authenticity of his character.
Elizabeth Peña played a prank on Brett Ratner in which she appeared on the set wearing nothing but her character's bomb squad vest. According to Peña, she thought Ratner would laugh and howl but instead he was extremely nervous and embarrassed.
When Lee shows Carter Consul Han's card, it shows that the Consuls first name is Solo. In Chinese, a person's family name is spoken and printed before their individual name. (Meaning that his name in Chinese, is "Han Solo.")
Brett Ratner was a big fan of Jackie Chan's Hong Kong movies. He felt that American audiences would not be familiar with the jokes in Jackie's other movies, and deliberately re-used some of his gags. For example, the scene where Inspector Lee accidentally grabs Johnson's breasts is a reference to Jackie Chan's film Mr. Nice Guy (1997).