According to author Jim Butcher he provided each main member of the cast with several of the books in the series. However, Valerie Cruz was the only member of the central cast who had read any of the books prior to filming.
The episodes were aired out of their original filmed order, and the two-hour pilot was never aired in its entirety during the shows run. An edited version of the pilot, titled "Storm Front," aired in the middle of the first season.
The character of Karrin Murphy became Connie Murphy for legal reasons after it was discovered that there is an actual police officer named Karyn Murphy in Chicago.
James Marsters, who did the narration for some of the audiobooks in the series, turned down the opportunity to audition for the role of Harry Dresden because he didn't want to move to Toronto in case the series was produced.
Originally Valerie Cruz auditioned for the part of Susan and Rebecca Mcfarland auditioned for the role of Murphy. Cruz, who read the original book, thought she fit the physical description of Susan.