Hongkong has a _modest_ social problem related to freeing unwanted pets into the wild. There are numerous billboards and buses adverts warning people not to do it.
On the other hand, there is very real urban legend of a salt water crocodile that was captured in early 2000s in the Hongkong wild. It was hunted for months. Authorities have no idea if was a release, or travelled from nearby (more tropical) region. Read more about Pui Pui on Wiki: https://en.wikipedia.org/wiki/Pui_Pui_(crocodile) She is even on show at the Hongkong Wetland Park. But if you want to see salties in the wild without too much effort or stress, you can do that in Singapore at a wetland reserve near Kranji.
