The Forbidden Kingdom

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."

The characters were mostly taken from Chinese mythology and adventure pulps. Lu Yan is a famous Taoist Saint (he is better known as Lü Dongbin, one of the Eight Immortals referenced in Jackie Chan's Drunken Master movies). The Jade Emperor is the ruler of the Heavens in Chinese myth. The Monkey King is from a sixteenth century fantasy epic by Wu Cheng En. Golden Sparrow was the name of the character played by Pei-Pei Cheng in several Shaw Brothers movies, like Come Drink with Me (1966). The White Haired Demoness is the anti-heroine of a pulp novel by Liang Yusheng (filmed twice) with the same title.

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.

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.