I recently visited Hong Kong. I am British. When I returned to the UK I noticed that I still had the white Immigration Card in my passport. Do I need to return this to the Hong Kong Immigration authorities? If I don't will it cause problems returning to Hong Kong?
If you are talking about the paper card that you filled out when you landed, then no. There is no need to return this. You can throw it away. There will be no issue on the next trip to Hong Kong.