- The name "Pig Sty Alley" (Zhu Long Cheng Zhai) is a play on the Chinese name for the Walled City of Kowloon (Jiu Long Cheng Zhai), a Chinese enclave in Hong Kong for much of the 20th Century, and well-known as a breeding ground of crime, slums and disorder. It was torn down in 1993.
- The "Landlady," played by Qiu Yuen, appeared in the 1974 James Bond film
Donut: [nearing death, grabs the landlord] With great power comes great responsibility...
Landlady: Donut, you are badly hurt. You must keep still.
Donut: This could be the end of a beautiful friendship!
Landlord: Oh, Donut. Tomorrow is another day!
Sing's Sidekick: Memories can be painful. To forget may be a blessing!
Sing: I never knew you were so deep.