Nick Cheung Ka Fai and Monica Mok Siu Kei in TO LIVE AND DIE IN MONGKOK had a passionate bed battle, which Ka Fai proclaimed that was the biggest challenge in the film. In this scene Siu Kei was willing to offer her body to repay Ka Fai for his help. One of Ka Fai's more violent personality exploded during the passion and began to ferociously attack Siu Kei. Ka Fai and Siu Kei performed very professionally, but their action was excessively passionate as they rolled off the bed. Ka Fai in order to protect Siu Kei's head landed with his hand first, but he injured his shoulder. The crew immediately took him to the hospital for treatment.
Ka Fai said, "Actually when we made this scene we already agreed on how to coordinate, but during the actual shoot we were too focused in our profession and got hurt. Siu Kei was very professional and gave a very wild performance." Mok Siu Kei said that she did not mind any intimate scene in the film. "Ka Fai was quite a gentleman, first he clearly told me where he would touch me. During the shoot the director also said that we performed very well, which made me very happy."