Sometimes when the locals talk in Cantonese, they tend to shout at each other. I was always scared that they may pull out a gun and shoot each other, if they are angry. However, I am told that it is normal to shout at each other in Hong Kong - this thing tends to happen when you are living in such close proximity to other people - you have to yell to be heard!! So do not worry about it.
English is widely spoken in Hong Kong but I had to chuckle when I saw this sign telling me to "Care the lovely plants".