Cheng Chang's storyline was completely improvised. Wong Kar-Wai discovered restaurant China Central by chance and, seizing Leslie Cheung's absence due to a concert tour, decided to keep shooting. So Chang's plot was created.
Tony Chiu Wai Leung was unaware that his character does boxing. Kar Wai Wong made Chiu Wai take boxing lessons and later filmed fight scenes that were cut from the final film. Wong said Chiu Wai's performance was improved because of the energy he had from boxing.