In the very first shot of the opening credits, the American flag over the harbor can be seen flying at half-mast. The reason was the assassination of President John F. Kennedy, shortly before the shot was filmed.
Alan Hale Jr. was on location in Utah filming a movie when he got a call to come back to Los Angeles to do a screen test for Gilligan's Island (1964). Hale rode a horse to the highway, hitchhiked to Las Vegas and flew to L.A. to test with Bob Denver.
It has long been stated that the entire cast never received residuals beyond the first four reruns of each episode. This was true for the entire cast except Dawn Wells. When the show was picked up by CBS and Wells was cast to replace Nancy McCarthy, she was married to her agent at the time. In her original contract she was to be paid $1200 per week plus the residual contract the six other castaways received. Her husband/agent said that should the show become successful. Wells would not benefit from receiving such a limited residual option. Believing the show would flop, the CBS executives humored Wells and her husband and put a clause in her contract giving her long-term residuals should the show ever syndicate. As a result from that clause, Wells has made literally millions of dollars as the years have gone by from syndication of Gilligan's Island. This was never public knowledge. Dawn and series creator Sherwood Schwartz are the only individuals to profit long-term from the series.
In the first-season credits, Russell Johnson and Dawn Wells were relegated to being simply "all the rest". That changed in the second season when Bob Denver demanded that they be given an equal share in the credits, thus changing the lyrics to "The Professor and Mary Ann". Sherwood Schwartz, who composed both themes, has said it didn't occur to him the Professor and Mary Ann would turn into prominent characters.
Alan Hale Jr. had a tendency to address people as "little buddy". Because of this, "little buddy" became the Skipper's signature term of affection for Gilligan. It is now widely used by fans as a nickname for Bob Denver.
The ship's name, S. S. Minnow, was not named for the fish but rather for Newton Minow, head of the FCC in 1961. Minow was the one who called television "America's vast wasteland". Sherwood Schwartz did not care for Minow so he named the soon-to-be shipwrecked ship after him, though he later said that Minow actually enjoyed the joke and that the two eventually exchanged regular friendly correspondence.
The first season had the cast using cups that were made from real coconuts. However, they found that the cups were porous and soaked through like they were sweating. Thus in the later seasons, the coconut cups were ceramic replicas.
Natalie Schafer's contract stipulated that there be no close-ups of her in the show. The reason was producers knew her real age, which was 13 years older than Jim Backus, who played her character's husband. It was not until years after the series ended that her co-stars found out her actual age.
"The radio" seen in virtually every episode was a Packard-Bell AM Radio, Model AR-851. The small silver handle and telescoping antenna were added by the prop department (despite the fact that AM radios do not use telescoping antennas). The antenna was likely added to lend credence to the castaways' ability to pick up radio signals so far from civilization.
Partly inspired by the 1939 film Five Came Back (1939) starring Lucille Ball. The characters in that film included a wayward pilot and co-pilot, a botanist and his wife, a sultry woman with a shady past, and a rich playboy and his homespun wife.
As the show progressed, producers planned to introduce a new character - a pet dinosaur - but decided against it because of the cost of special effects. The character, however, was incorporated into the animated Gilligan's Planet (1982).
With the show ready to go to air, Sherwood Schwartz had yet to come up with a theme song. When it came time for him to submit one, he decided to make the theme a story of how the characters got shipwrecked. It was then titled "The Ballad of Gilligan's Island".
The premise required that the characters use various devices that had to be constructed from only the various materials found on a tropical island. Thus the props had to be specially made and the prop department enjoyed the challenge which was a change of pace from simply bringing in the standard props from storage. The bamboo foot pedal-powered car used in one episode was a particular favorite with the cast queuing up to try it out.
Four vessels were used as the SS Minnow. One was towed to Kauai, Hawaii for beach scenes, one was rented in Honolulu for the original opening credits, and one was built at CBS Studios in the second season. The fourth one was used in the second-season opening credits. A subsequent owner was sailing it south from Alaska when it ran aground on a reef off the coast of British Columbia. It was purchased for salvage and restored. It was offered for sale in B.C. for $99,000. It was listed as a 37-foot twin-diesel, mahogany Wheeler Express Cruiser which sleeps five.
The original series pilot had another actor in the role of the Professor and two female castaways, Ginger and Bunny, both secretaries. Because of the cast changes, the original pilot was unairable until it was broadcast by TBS in 1992.
There has always been the debate of who is more popular, Ginger or Mary Ann. Though there is no real answer to that question, the consensus seems to be Dawn Wells got more fan mail from young boys, while Tina Louise got more fan mail grown men because Mary Ann was the girl next door that every teenaged boy would love to go out with, while Ginger was every man's fantasy.
At one point during development, producers considered including a young nephew of the Professor's among the castaways. However, it was determined that given the child-like nature of Gilligan, a child among the castaways would be redundant.
'Weird Al' Yankovic has written two songs about Gilligan's Island. The first is a parody of "Wild Thing" called "Isle Thing" where a guy dates a girl who is obsessed with "Gilligan's Island". The second is a concert only song called "I'm In Love With The Skipper" which is sung from Gilligan's point of view about Gilligan really being in love with the Skipper. During the song he shows clips from the show that actually seem to prove the song to be true. He also sings part of the theme song in his song "Amish Paradise" and mentions watching the show in "Stop Draggin' My Car Around" and "Couch Potato."
Sherwood Schwartz claimed that, contrary to popular belief, "Robinson Crusoe" was not the inspiration for the series, even though it was one of his favorite books and was referenced in the closing song.
It is revealed in Gilligan's Island: Two on a Raft (1964), (the second pilot) that the name of Mary-Ann's hometown was Winfield, Kansas. It is sometimes mispronounced as Horner's Corners, but that was the home of her boyfriend, Horace Higgenbotham.
The producer and the rest of the cast all experienced life longevity. Sherwood Schwartz lived to be 94 and Natalie Schafer (Lovey Howell) lived to 90. The shortest longevity was from Alan Hale Jr. (the Skipper), who died at 68. Bob Denver (Gilligan) died at 70, Russell Johnson (the Professor) died at 89. At the 50th anniversary on September 26, 2014, only two cast members still survived, Tina Louise (Ginger Grant) and Dawn Wells (Mary Ann). The two ladies were 80 and 75 years old respectively. Also, three of the cast members died within 21 months of each other. Jim Backus (Mr. Howell) died in July 1989 at 76, the first of the cast to pass away. Six months later Alan Hale Jr. passed away, followed by Natalie Schafer 15 months later. Another actor would not die for more than 14 years later, the series star Bob Denver.
Each of the three actresses on Gilligan's Island were married only once and their marriages were fairly short term. Natalie Schafer (Mrs. Howell) was married nine years, Dawn Wells was married five years, and Tina Louise was married four years.
Schafer had said she initially did the pilot to Gilligan's Island (1964), for the free trip to Hawaii. Afterwards, Schafer was in Puerto Vallarta, Mexico, on holiday when she got a telegram from the States. She read it and burst into tears. Everyone had thought Schafer's mother (who was ill at the time) had died, and offered their condolences, but Schafer had said no she didn't die, the reason she was crying was because the pilot for "Gilligan's Island" sold, and she had to stay in Los Angeles, and could not move back to New York City.