The commercial celebration at pubs are not uncommon and the Universal Studios Singapore also of special events for that but there is a residential occupied by more wealthy American expatriates.
Last time I went to check it out was in 2016:
https://steemit.com/photography/@ace108/halloween-2016-in-singapore-2016-by-ace108
and the year before.
https://steemit.com/photography/@ace108/happy-halloween-trick-or-treat-in-singapore-by-ace108