Andy Hui's character, Kei-on is a combination of two characters from Japanese Comic, Doreamon, which are Suneo (where Andy Hui gets the weird hairstyle and wealthy background) and Giant (in the Cantonese version of Doreamon, Giant is called Kei-on and he is a big bully). Dicky Cheung's character is also a reference to Doraemon's main character Nobita (Cantonese version is called Dai-hung, always a bully victim of Giant and Suneo), and Charlie Yeung's character is obviously refers to Shizuka (Nobita's love interest in Doraemon). In fact, in the film there is also a reference to Doraemon comic. Once Hung discover the identity and ability of those three 'future cops' he exclaim that "it is just like Dai-hung (Nobita) has three Ding-dong (Doraemon's name in Cantonese) altogether!"
While Vega is originally portrayed as a villain and Ken as one of the main characters, this movie reversed it though Ken switched sides in the end.
This film includes 'Andy Lau', 'Jackie Cheung', and Aaron Kwok who because of their popularity as an actor and pop singer during 90s, were dubbed as "The Four Heavenly Kings" of Cantopop along with Leon Lai. Years later, due to his success in music scene, co-star Andy Chi-On Hui, was named as one of their successor dubbed as the "New Four Heavenly Kings"
The song played during the end credits and also Broom Man sang during his music class was actually a Cantonese interpretation of a Tagalog ballad titled "Sana Kahit Minsan" (literally Hopefully, Even Just Once in English) originally by Filipino singer Ariel Rivera.
The characters "Choy-Nei" and "Kei-On" are references to the original names of stars Charlie Yeung (Yeung Choi-Nei) and Andy Hui (Hui Chi-On).