In the first-season opening credits, Russell Johnson and Dawn Wells were relegated to being simply "the rest," allegedly due to Tina Louise's insistence that no one be listed after her in the opening credits . 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. was on location in Utah filming a movie when he got a call to come back to Los Angeles to do a test for the series. He rode a horse to a nearby highway, hitchhiked to Las Vegas and flew to L.A. to test with Bob Denver.
Alan Hale Jr. had a tendency to address people as "little buddy". Prior to this series, Hale played a guest role on The Andy Griffith Show (1960) in Season 2 episode 13: The Farmer Takes a Wife (1962), in which he refers to Don Knotts' character Barney Fife, as "little buddy" on several occasions. as well. This trait was written into the series and "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 island shown in the opening and closing credits is actually located in Kaneohe Bay, about a mile offshore from the island of Oahu, in Hawaii.
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.