Director Chris Nahon had to slow down the fight scene between Jet Li and Cyril Raffaelli because they were moving too fast for the camera.
Cyril Raffaelli knows how to perform the one-and-a-quarter backwards somersault-kick he does in the final fight scene without the aid of wires. There were at least two takes without the wire, but supposedly Cyril was moving too fast for the camera. Wires were added in for "clarity".
The style of action in this movie was heavily influenced by comments made during series of messages posted by fans on the Jet Li website forum, immediately after the release of Roméo doit mourir (2000) in the United States. The fans wanted more realistic fighting as in Jet Li's movie Fist of Legend: La Nouvelle Fureur de Vaincre (1994).
In the scene were Jet Li attacks Max Ryan (Lupo), they were supposed to film the dialog scene separately from the fight that follows. However, after the dialog, the director didn't say "cut", and so Jet attacked Max. The take is in the final film - along with Max Ryan's very realistic frightened expression.
The tunnel where Jet Li is ambushed by French policemen is the same tunnel at Pont d'Alma in Paris where Princess Diana died.