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 father appears as a dental patient, and his grandmother, Myrtle Vail, appears as Seymour's hypochondriac mother. Dick Miller, who had starred as the protagonist of "A Bucket of Blood" was offered the role of Seymour, but turned it down, instead taking the smaller role of Burson Fouch. Production at the "Bucket of Blood" sets was compressed into three days of cast rehearsals, immediately followed by two days and one night of principal photography. It had been rumored that the film's shooting schedule was based on a bet that Corman could not complete a film within that time. However, this claim