Due to the intensity and complexity of the sequence, both Donnie Yen and Collin Chou agreed that their fight sequence at the end of the film was the hardest shoot they had ever done in their respective careers
In the parking garage scene, it took Yu Xing 39 takes in order to complete the simple shot of him leaping over the gate when attacking the man in the car. Donnie Yen attributed Yu's difficulty to nerves, as this was his first movie with Yen and the scene was his first to be shot in the film. An outtake of Yu crashing through the gate and breaking it is included in the movie's final credits.
Donnie Yen originally planned to have a much larger fight scene at the driving range, which would involve a longer brawl between the two gangs followed by his character showing up to stop it. The scene was cut down due to lack of funds and the inability to get permission to shoot additional scenes at the location.
The trivia item below may give away important plot points.
Director Wilson Yip originally shot a different ending, in which Donnie Yen was shot and killed following the final fight with Colin Chou. After screening it, he decided to change the ending to a more positive one, with Yen surviving.