Will Ferrell was the voice of American President George W. Bush when speaking to Kelly Robinson (Eddie Murphy) over the telephone.
At the request of director Betty Thomas, Darren Shahlavi lost thirty pounds so as to be the same size as Eddie Murphy during the boxing scenes.
Initially, Owen Wilson admitted he was a little nervous about performing opposite comedy legend Eddie Murphy, who was one of his comic idols. Wilson said: "This is the first time I've had to work with someone who is so incredible at improvisation. At first, it was difficult to keep up with Eddie. But slowly I started playing off his riffs. I don't know if that's what people mean by on-screen chemistry. To me it's a feeling that you are really in a groove with what the other guy is doing."
Like Owen Wilson, Famke Janssen got to spar with Eddie Murphy on-screen, a process Janssen, like Wilson, also found daunting at the outset. She said, "There's a scene in which Eddie and I first meet and he just kept tossing lines at me and I kept going with it. It was really scary, but once I got used to it, a lot of fun as well."
Although the filmmakers were lucky to secure the Buda Castle, the use of that location presented them with some challenges. Director of photography Oliver Wood explained: "The Castle was honeycombed with caves underneath. So every time I wanted to bring in a heavy piece of equipment in for a shot, we ran the risk of the equipment sinking into the road down to the caves underneath."
Will Ferrell: Uncredited, as the voice of the American President when speaking to Kelly Robinson (Eddie Murphy) over the telephone.