A full-scale replica of the Kowloon Walled City, reported to be almost identical to the original, was constructed for the shoot. Contrary to claims that the set was demolished immediately afterwards, substantial sections were preserved and reused in public exhibitions, allowing the Kowloon Walled City's legacy to be appreciated by a much wider public.
The project had been under development since the 2000s.
Hong Kong's official entry for the 'Best International Feature Film' category at the 97th Academy Awards in 2025.
Cyclone is presented as an autistic martial-arts master — a departure from the original manhua, 'City of Darkness', where he is portrayed as a conventional martial-arts master with no indication of autism.
At certain points the music resembles Nightwish's cover of 'Walking in the Air'.
