When Dragon and Tiger fight, Tiger does a Thai Boxing ritual called "Wai Khru Ram Muay" which is a ceremonial dance and stretching routine often performed by Thai Boxers before a fight. The actor that plays Tiger (Ken Lo) is a former Muay Thai Champion.
Dragon's love interest in this movie is played by Miki Yeung - a member of the Hong Kong pop band "Cookies". In the previous Dragon film ("Dragon Loaded 2003"), Dragon's love interest was played by Stephy Tang who is also a member of the all-girl pop band.
When Lung Wai first meets Tiger, Tiger asks him if he is dressed to audition for a sequel to "Project A". Project A is a 1983 Hong Kong film that starred Jackie Chan and Ken Lo, the actor that plays Tiger, was Chan's personal bodyguard in the mid 1980's.