Steve Martin had such respect for Peter Sellers that when he was asked to take over the role of Clouseau, he put off the decision to accept it until after he had already worked out the character's accent and run several ideas for scenes past director Shawn Levy.
Jackie Chan was considered for the part of Clouseau's Chinese assistant, Cato Fong. But the filmmakers decided they didn't want to use a politically incorrect character, and replaced Cato with the Frenchman Ponton.
Originally, the animated title sequence was going to be done in CGI, but the filmmakers decided to stick to traditional, hand-drawn animation instead. This animation was directed by Bob Kurtz, who had worked on some of the "Pink Panther" shorts. The CGI title sequence appears as an extra on the DVD, and is partly used as menu animation.
The cameo appearance of Clive Owen can be seen both as a nod to the fact that Owen was rumored to be a contender to replace Pierce Brosnan as James Bond in Casino Royale (2006) (denied by both EON and Owen), and a tribute to Peter Sellers (the most famous actor to play Inspector Clouseau) who also parodied James Bond in the spoof film, Casino Royale (1967). Owen's role was originally intended for Pierce Brosnan, but his contract with EON specifically prohibited him from appearing as a spy in a tuxedo for at least five years after leaving the role of 007.
In the early stages, Paul Giamatti was considered for the role of Dreyfus and there were even plans for a running gag that would have had the Pink Panther animated character worked into the actual story by having him appear as Dreyfus' madness-induced hallucinations.
According to the 2004 teaser trailer credits David Newman was attached to compose the film's score at one point. The film's final composer, Christophe Beck, was originally hired to do the score, than a few months later he was off the project and Newman came in. Then a few months after that, Beck was back on.