Donnie Yen was offered to reprise the role of the Monkey King. However, due to both schedule conflicts and his views on both the make up and physical work that had to be done, he declined to return. Aaron Kwok, who previously played by the Bull Demon King in the original film, was selected to take over the role of Sun Wukong/The Monkey King.
Aaron Kwok had to spent more than 6 hours to fit in one monkey fur-suit. Because of the extreme inconvenience of going restroom, Aaron Kwok basically did not drink or eat even if he excessively sweated when shooting fight scenes. Also to avoid skin allergies from the monkey fur-suit, he had to use compress air to evaporate his sweats while wearing the suit--in the midwinter days.
It took more than five hours for Aaron Kwok and Chung Him Law to wear and take off their makeups, and most cast members suffered from the special effects makeup. Shaofeng Feng, who plays Tangsanzang, was envied by other actors because his role took the least efforts to prepare. However, he fell from his horse in the beginning of film shooting. While doctor recommenced Feng to rest for two months, he came back in two weeks.