If you are going to Hong Kong in late October make sure you soak in the Halloween atmosphere. Unlike in America, don't expect to find any trick-or-treading in HK except maybe Stanley / Park Island / Sai Kung / Discovery Bay... etc.  Halloween in Hong Kong is more about commercial activity (much like the X'mas seasons) and entertainments for young adults.  However, young adults often dress up (with costume) for clubbing and bar hopping in LKF on Holloween night (or the closest weekend to the night) and most etablishments will give out discounts / coupons / waiver of admission fee for those who dress up.  Also, many restaurants will put up some 'special menu' (like a pumbkin menu or everything in black & orange... pretty cliche). Shopping malls will do themed decorations / promotion...

What about Ocean Park and Disneyland?

The two major theme park in town will turn into giant haunted mansion at night doing special night-admission starting 7-ish pm till midnight. Both of the parks hire hundreds of extras to pop-up in scary costumes to scare people (yes, even at Disney!). Tickets for night-admission are sold separately and required to gain access to the rides / haunted mansions. Day tickets holders are supposed to leave the park at a certain time but they have been known to not really enforce this requirement. Outside the area reserved for those with night tickets, a few extras will be stationed to scare people walking nearby!  So you can still experience a bit of the Halloween atmosphere even if you don't pay the extra fee.

Oh, and believe it or not , even the religion related theme park the Noah's ark has a tag along!! But of course they are 'celebrating' the 'All Saint Day' and defend themselves against the pagan / devil worshipping festival...