On the first day of filming, Lam collapsed due to a heat stroke. He stayed with the project to keep filming.
In 2014, the film's titled changed from Hustle to Wild City.
Lam described Wild City as belonging to a "City Trilogy" along with the films City on Fire (1987) and Full Alert (1997). Lam described them as "films, that are all set in Hong Kong and are about people who are lost in the city. In Wild City the theme is about the temptation of money, and how it seduces the protagonists, but also forces them to challenge the plutocracy."