According to Jackie Chan, when he and Jet Li shot their fight together, they found it relaxing and easy: "I have not worked with someone who I'm comfortable with, in terms of movements, rhythm, and natural reactions, in the last ten years. I have done many fight scenes with others, but there were usually more than ten takes, which is a waste of time, as the person may forget his moves and unnecessary injuries. When I fought with Jet, our actions were quick. We also didn't have to do the same stunt over twenty times."
At first, the original theatrical trailer revealed the overall story of Michael Angarano (Jason Tripitikas) as being the central character that unites Jet Li (The Monkey King) and Jackie Chan (Lu Yan) as side characters during his adventure. Fan reaction and feedback was so negative to this reveal that a new trailer was hastily edited that only focused on Jet Li and Jackie Chan's interactions, with no mentions of Michael Angarano, in the hopes that the film wouldn't receive bad word of mouth due to the pair only having supportive roles before it debuted.
This movie marked the first collaboration between Jet Li and Jackie Chan. However, Chan has said he did not consider this movie to be "THE Jackie Chan-Jet Li film", as neither of them had anything to do with directing, producing, or choreographing.
When the time came to film the cherry blossom scene, the filmmakers were horrified to find the all the plants had gone bare in the meantime. The crew was ordered to glue thousands of fake blossoms to the branches.
Before filming began, the entire cast did a costume fitting and a script read-through. Certain dialogues were altered to suit the different actors' English speaking abilities, since the majority of the cast had English as their second language.