The film was based on a real-life corruption scandal in the mid 1980s that involved the father of co-writer and director James Gray.
For Leo's and Willie's fight, Mark Wahlberg and Joaquin Phoenix agreed to actually fight each other. Although they wore knee and elbow pads, everything on-screen is the two of them beating each other up. There are no stunts, and the entire thing was done in two takes, from three different angles. The next day, they were black and blue.
Just before the fight scene, Joaquin Phoenix actually hit Charlize Theron, and really did take a tumble down the stairs.
Although theatrically released in the fall of 2000, the film was shot during the spring and summer of 1998, and was originally slated for theatrical release in the fall of 1999. Studio and production problems, however, delayed the release for a full year.
The film was beset by significant post-production drama over creative differences about its tone and content, as detailed in the book "Down and Dirty Pictures: Miramax, Sundance and the Rise of Independent Film" by Peter Biskind. It appears on a 2017 list in "The Telegraph" in an article entitled "Harvey Scissorhands: 6 Flms Ruined by Harvey Weinstein."