Bob Denver was not the first choice for Gilligan; Jerry Van Dyke turned down the role, believing the show would flop, and instead starred in My Mother the Car, which is often cited as one of the worst TV shows ever and was canceled after one season.

Carroll O'Connor auditioned for the role of the Skipper but couldn't nail the right combination of gruffness and warmth; Alan Hale Jr. eventually got the part, and his wife said he 'was born to play the Skipper'.

The role of Thurston Howell III was written specifically for Jim Backus, but he was initially unavailable and too expensive for the show's limited budget until a deal and budget increase were arranged.

Natalie Schafer had a no-close-ups clause written into her contract and took the role mainly because the pilot was filmed in Hawaii, viewing it as a free vacation since she was convinced the show would never succeed; she also kept her real age secret from the entire cast and crew.

Tina Louise believed she had been hired as the show's central star and clashed with producer Sherwood Schwartz over her character Ginger, who was originally written as a harsher temptress before a compromise turned her into a Marilyn Monroe/Jayne Mansfield type.

Russell Johnson, who played the Professor, had been a real WWII bombardier and navigator whose B-25 was shot down in 1945, killing the copilot and breaking both of Johnson's ankles; he was initially reluctant to take a supporting TV role but was talked into auditioning by his agent.

Dawn Wells, a former Miss Nevada, beat out Raquel Welch and Pat Priest for the role of Mary Ann.

The pilot episode's final day of filming, November 22, 1963, coincided with the assassination of President Kennedy; the cast and crew learned the news between takes in Hawaii, and a flag flying at half-staff can be spotted in the background of the season one opening credits.

Four different boats were used to portray the SS Minnow, including one rented in Honolulu's Ala Wai Yacht Harbor and another, the Bluejacket, which later ran aground on a reef in Alaska's Hecate Strait in 2006.

The SS Minnow was named after Newton Minow, the FCC chairman whose 1961 speech criticized television as a 'vast wasteland' of bad programming, including 'formula comedies about totally unbelievable' characters.

Star Bob Denver personally pushed studio executives to add Russell Johnson's and Dawn Wells' names to the theme song in season two, threatening to have his own name removed if they weren't included; the studio initially refused due to cost but eventually caved.

The dream sequence episode 'The Sound of Quacking' was filmed on the actual Gunsmoke set, and Gilligan's Island itself was canceled in part because CBS moved Gunsmoke into its Monday timeslot to save that long-running series.

Because cast members had been assured by Sherwood Schwartz that a fourth season would happen, some had already bought houses near the set when the show was abruptly canceled while they were on vacation.

Tina Louise was the only original cast member who refused to appear in any of the three television film sequels due to her ongoing disputes with the producers, and was replaced by Judith Baldwin and later Constance Forslund.