Show creator Daniel Knauf‘s original story pitch to HBO included elaborate character biographies, which he gave to the actors, the writers and the studio as an overview over the series’ intended plot. These biographies were rewritten before the filming of the first season began. Receiving little to no mention in the series afterwards, the original character backgrounds were summarized on the official HBO website. After the show’s cancellation, the writers revealed future character arcs and forwarded all original biographies to fans as part of the show’s so-called “Pitch Document”. Due to their nature, these sources do not offer canon information per se, but provide a frame for the characters’ motivation throughout the series.

The thematic and period setting of Carnivàle required an unusual casting approach. While some actors were hired for their genetic disabilities, most actors were specifically cast for their unique and distinct looks to fit the 1930s period. Award-winning costumes and make-up enhanced the illusion. Reviews generally lauded the actors and characters, and several actors received award recognition for their performances.