The pilot episode of "Gilligan's Island" is available on the season 1 DVD set. Streaming sites such as Amazon offer the first telecast episode as part of the first season. Netflix offers the DVD set for rental. Websites that stream from the DVD set may show the pilot.
The pilot episode, "Marooned," did not air until 1992, as Bob Denver recounts on his website. The pilot's theme was a calypso song written by John Williams, later famous for his movie themes, such as "Star Wars." The female leads in the pilot, Ginger and Bunny, played by Kit Smythe and Nancy McCarthy, were both secretaries. Ginger was the practical brunette. John Gabriel, who played the Professor, was a hunky leading man type, in Bob Denver's recollection.
The first broadcast episode, "Two on a Raft," established the cast and theme song that continued throughout the series. This episode is sometimes incorrectly called the pilot, as the actual pilot was unseen for almost 30 years.