The screaming woman sound used as a doorbell is Fay Wray's screams from King Kong (1933). Her unique scream has made her known as the "Scream Queen" of movies.
''We should have taped the first read-through of the script and released it as a comedy album. It was a classic," reported many of the production personnel after first rehearsal session together of the cast and crew. According to writer Neil Simon, "the first reading is where I see what works and what doesn't. It was the best one I've ever witnessed for any of my plays or films." Simon was on the set of this movie every day.
Immediately after completing this movie, Peter Sellers was so convinced it was going to bomb, he convinced the producers to buy back his percentage share in the movie.
Peter Sellers reportedly played several practical jokes on cast and crew during filming, including once calling Neil Simon up and imitating co-star Sir Alec Guinness and demanding a rewrite of a key scene in the middle of the night. Neither Guinness nor Simon were amused.
In the television edit of this movie, which contains footage not released theatrically nor on home video, Keith McConnell and Richard Peel appeared at the end as "Sherlock Holmes" and "Doctor Watson," respectively.