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
Little Shop of Horrors (musical) Orin Scrivello, is killed by suffocation from laughing gas instead of being stabbed with a dental instrument as in the film. His abusive relationship with Audrey is added to the musical to give Seymour a motive to kill him. In the film, Seymour murders several innocent bystanders, and Mushnik tricks a thief into looking for money inside the plant, which eats the thief. In the musical, Seymour tricks Mushnik in the same way when Mushnik plans to turn Seymour over to the police. The two neighborhood girls in the film are replaced in the musical by a chorus of three