Loosely based on the story of real-life Hongkongese corrupt police sergeant Lui Lok (in Mandarin: Lü Le) who was dubbed the 'HK$500 Million Sergeant' and nicknamed Tiger Lui (Lui Lo-fu). The character was renamed as Lee Rock in the film with different Chinese characters whose pronunciation are similar in Cantonese (Lui Lok) but different in Mandarin (Lei Luo).