It looks as though the Philippines reference in the credits was related to some of the helicopter sequences towards the end of the film. The aforementioned big explosion however was filmed locally at a place I only really found out about fairly recently: Shing Fung Studio.
Shing Fung is a large outdoor space situated in Ho Chung village in Sai Kung. In fact, I even walked past it earlier in the year on a hike from Pak Fa Lam to Ho Chung and grabbed a snap of the road sign as I passed, not realising it was a fairly well established company.
成豐片場 - Seng Fung Pin Cheung
Anyway, the studio lot is large enough to have erected the following set, and if you click on the company link I gave above you'll see they have several studio buildings as well as a pool for underwater filming and a host of other services.
Jude also told me the place has been used many time before including: Extreme Crisis (1998), Enter the Eagles (1998), King of Comedy (1999), Gorgeous (1999) and Zhang Ziyi's Dining Out Visa Card advert (2001?) and, no doubt, many many more.