Some of the scenes were directed by uncredited producer Hark Tsui.
Chief Inspector Waipong Wong:
That bastard is still following.
Inspector Kwok-Keung Lun: I know I've failed. Tried twice to meet the guy.
Chief Inspector Waipong Wong: I didn't mean you. I meant those guys are tailing us again.
Inspector Wong and his partners drives a 1975-1983 BMW 3-series coupe during all times in the movie except after being ambushed after leaving the lab. then it suddenly changes to a BMW 5-series of the 1982-1988 generation, a four door proper sedan of the same color as his previous car. In all subsequent scenes he is driving his original car again.
The German video release by VMP is cut by about 2 minutes to remove violence.