The Little Shop of Horrors recalled "at first they told me it was a detective movie; then, while I was flying back [to make the movie], I think they wrote a whole new movie, more in the horror genre. I think over a weekend they rewrote it." The screenplay was written under the title "The Passionate People Eater". Welles stated, "The reason that "The Little Shop of Horrors" worked is because it was a love project. It was "our" love project." The film was partially cast with stock actors that Corman had used in previous films. Writer Charles B. Griffith portrays several small roles. Griffith's
The Little Shop of Horrors has been denied by Mel Welles. According to Joseph, Corman shot the film quickly in order to beat changing industry rules that would have prevented producers from "buying out" an actor's performance in perpetuity. On January 1, 1960, new rules were to go into effect requiring producers to pay all actors residuals for all future releases of their work. This meant that Corman's B-movie business model would be permanently changed and he would not be able to produce low-budget movies in the same way. Before these rules went into effect, Corman decided to shoot one last film and scheduled it