I scratched my head for a while wondering if this was filmed in a studio or actually done on location and have come to the conclusion that it was on location. Why? Well, because thanks to the Facebook group: Kowloon Walled City 九龍城寨 (九龍城砦), I found a picture of the temple front allowing me confirm its identity.
The above picture was grabbed from the title sequence, but we return to the same location later with ol' Gibbsy and Van Damage as they enter what is supposed to be the venue for the Kumite. I believe the actual fight scenes were filmed at Clearwater Bay Studios on Ying Yip Road.
A nice touch with the pot plant...
So anyway, here is the picture from the above mentioned Facebook group. Incidentally, this Tin Hau temple has been mentioned elsewhere in the arts world and I distinctly remember Martin Booth making a reference to it in his memoir "Gwei Lo/Golden Boy".