The concept for having an episode dedicated to The Lone Gunmen arose when the show's producers were forced to start production of the fifth season in the last week of August in Vancouver, but still needed series stars David Duchovny and Gillian Anderson for the filming of "The X-Files" movie in Los Angeles. Writing duties fell to Vince Gilligan, who initially drafted a story about nanotechnology, before changing to the origins of The Lone Gunmen on behest of series creator Chris Carter. In addition, "Unusual Suspects" served as a cross-over with the NBC series "", featuring Richard Belzer's Detective John Munch character. Gillian Anderson as main character FBI Special Agent Dana Scully is absent in the episode.