To achieve Dave's gaunt appearance, Woody Harrelson sought advice from Christian Bale. Bale told Harrelson to eat very little and run as fast as possible.
For a promotional stunt, Woody Harrelson was tasked with answering a Reddit AMA (Ask Me Anything), but he barely answered any questions, except for those that were about the movie. Whenever he actually replied to unrelated questions, his answers were just plugs for Rampart. As of 2022, it is still referred to as "the worst AMA of all time" by users of Reddit and now has a legendary meme status.
"Klub Satan" was filmed in an old slaughter house in downtown Los Angeles.
"Rampart" was slated to be the name of the television series The Shield (2002) which is a show about a veteran Los Angeles cop who goes renegade and becomes increasingly corrupt.