I'm not doing these scenes in any kind of order so here is a shot from a little bit into the film when we find out where Zhongkang (Paul Chin's character) is working: at a car workshop.
The clue for this location can be seen in the background and perhaps is only obvious to people who have been to the location. It's changed a lot but the house in the background is unmistakable and can be seen when a taxi is called for one of the workshops clients who also happens to be Zhongkang's estranged mother.
The house I've ringed is the famous Shaw Bros house with its odd window shades and smaller arched window openings underneath. The terrain has changed quite a bit because the new office block was built at about the same location where the workshop would have been built but the embankment seen behind the taxi cab is still there - albeit on the other side of a concrete wall.