film's plot was adapted from a self-titled story published in a 1968 issue of R. Crumb's Head Comix, while the second part is derived from "Fritz Bugs Out", which was serialized in the February to October 1968 issues of Cavalier, and the final part of the story contains elements of "Fritz the No-Good", first published in the September/October 1968 issue of Cavalier. The last half of the film makes a major departure from Crumb's work. Animation historian Michael Barrier describes this section of the film as being "much grimmer than Crumb's stories past that point, and far more violent." Bakshi stated that he deviated from the comics because he felt that the strips lacked depth: It was cute, it was sweet, but there was nowhere to put it. That's why Crumb hates the picture, because I slipped a couple of things in there that he despises, like the rabbis—the pure Jewish stuff. Fritz can't hold that kind of commentary. Winston is 'just a typical Jewish broad from Brooklyn'. ... [The strip] was cute and well-done, but there was nothing that had that much depth. Bakshi's unwillingness to use anthropomorphic characters that behaved like feral animals led him to rewrite a scene in "Fritz Bugs Out" where Duke saves Fritz's life by flying while holding Fritz; in the film, Duke grabs a railing before the car crashes into the river, a solution that Bakshi wasn't entirely satisfied with, but prevented him from having to use any feral animal behavior in that scene. In the film, there are two characters named "Winston" – one appears at the beginning and end of the film, the other is Fritz's girlfriend Winston Schwartz. Michael Barrier notes that Winston Schwartz (who appears prominently in "Fritz Bugs Out" and "Fritz the No-Good") never has a proper introduction in Bakshi's film, and interprets the naming of a separate character as Bakshi's attempt to reconcile this; however, the two characters look and sound nothing alike. Bakshi intended to end the film with Fritz's death, but Krantz objected to this ending, and Bakshi eventually changed it to the final ending. Casting The film's voice cast includes Skip Hinnant, Rosetta LeNoire, John McCurry, Judy Engles, and comic book distributor/convention organizer Phil Seuling. Hinnant, who would become known as a featured performer on The Electric Company, was cast because he "had such a naturally phony voice", according to Bakshi. Bakshi and Seuling