Gore Vidal, who wrote the original play, was extremely upset with the choice of Jerry Lewis as the lead in the movie version. On Broadway Vidal's play ran for 388 performances between Feb 7, 1957-Jan 11, 1958 and won Cyril Ritchard, originator of the Kreton character, a 1957 Tony Award nomination for Best Actor in Play. However, Lewis was a star, 12 times named to the Top Ten list of Box Office Stars, six times with partner Dean Martin (with whom he was the top star of 1952), and six times solo (ranking as high as #3 in 1958). He got the part.
Producer Hal B. Wallis considered either Lewis, Alec Guinness or Danny Kaye for the lead role. Gore Vidal told interviewers that Wallis had promised him that David Niven would play the part.
A poster for this film can be seen in Breakfast at Tiffany's (1961). It's on a wall in the final scene in the alley.
Prior to its successful Broadway run, "Visit To A Small Planet" was first aired as a television play on May 8, 1955. The stage play opened on Broadway February 7, 1957 at the Booth Theater, where it ran for 388 performances.