McGarrett finally caught Wo Fat in the final episode of the series. However, at the end of the episode, Wo Fat can be seen digging into his boot and taking out a file leaving it open for a possible reunion episode.
Jack Lord was the only one of the cast to stay with the series during it's entire 12 year run. Kam Fong (Chin Ho Kelly) left after the 10th season. James MacArthur (Danny Williams) left after the 11th season.
Opening montage consists of: Breaking wave, which first appeared in the film Surfari (1967); a hula dancer, played by now-college professor Helen Kuoha-Torco; the "Lady Columbia" statue at the National Cemetary of the Pacific. Model Elizabeth Logue running down the beach; close-up of Ms. Logue from a side view; then 13-year-old local resident Mel Kinney; Elizabeth Logue turning toward camera; red neon sign, formerly the Tops restaurant in Waikiki Diamond Head; flashing blue light; Aloha Tower, Honolulu; Ilikai Hotel.
Richard Boone (one of televisions biggest stars for having played Paladin on the 'Have Gun - Will Travel (1957)') was Leonard Freeman's first choice to play McGarrett. Despite the fact the Boone already lived in Hawaii, the actor turned down the role.
Even though the Khigh Dhiegh made 15 appearances as the villainous Wo Fat, he and Jack Lord (McGarrett) only appeared on screen together four times throughout the series run, including the pilot and the series finale.
In the opening title sequence, a hand can be seen loading a .38 snub nosed revolver then spinning the cartridges. The gun is being loaded with spent shells - bullets that have already been fired. The depression where the firing pin strikes the cartridge is clearly visible on all shells loaded.
For the ninth season, the Five-O offices moved out of the Iolani Palace and into an office building down the street (they moved back for the tenth season). Part of the reason was that the Iolani Palace itself was undergoing a facelift; the other part was that CBS was building a new studio for the series, which wasn't ready in time for the early episodes. The Five-O office scenes were actually filmed in the office building, which was introduced in each ninth-season episode by showing the Iolani Palace with scaffolding over its facing and then quickly panning down the street to the office building. Sometimes an exterior shot of the office building would show McGarrett pacing in front of his "new" office window.
James MacArthur left the series after Season 11. In a 1996 interview, he revealed that he had become tired, and wanted to do other things. It was also reported that there were delays in the decision to renew the show for another season, and James MacArthur took another job that was offered.
Magnum, P.I. (1980) began production soon after this series wrapped its last episode. In order to keep some sort of continuity, reference to characters from this show were included in early episodes of Magnum. However, a plan to have Jack Lord appear as McGarrett never came to pass. Lord retired from acting after the series went off the air. Second half of first episode of Magnum, P.I. makes reference to McGarrett when speaking about the bad assignments for Dan: "Putting Dan on this stuff is like making McGarrett the meter maid on Waikiki."
Other than Wo Fat, other notable adversaries for McGarrett that appeared in more than one episode included mob bosses Henore Vaschon (played by Harold Gould) and Tony Alika (played by Ross Martin), pimp Big Chicken (played by Gavin MacLeod) and the Robin Hood-like Lewis Avery Filer (played by Hume Cronyn).
Besides Steve (Jack Lord), Danny (James MacArthur), Chin (Kam Fong) and Duke (Herman Wedemeyer) all went through suspensions from Hawaii Five-O during the show. Danny and Steve were the only ones ever charged with murder.
In the episode "The Singapore File" McGarrett flies to Singapore to retrieve a witness, and returns to Honolulu. Singapore was actually downtown Honolulu. At the end of the episode, they are at a temple in Manila; they were actually at the Valley of the Temples in Kaneohe, Hawaii.
McGarrett supposedly had his office in Iolani Palace; the actual palace used by the last kings and queens of Hawaii. As of 1969, the Palace had fallen into disrepair after years of abuse and neglect. Restoration was begun, and the Palace can now be toured for a $20 fee.
Al Harrington and Herman Wedemeyer both appeared in different roles on the show before assuming the roles of Ben and Duke respectively. Wedemeyer was in the very first episode playing Honolulu police Lt. Balta.
Almost all of the regular actors who starred or had recurring roles on the series before the final season (including Zulu, James MacArthur, Al Harrington, Kam Fong, and Doug Mossman), eventually left the series. Jack Lord and Herman Wedemeyer continued to play McGarrett and Duke, respectively, even into the last season. (Mossman appears in one episode of Season 12, but not as a member of Five-O.) The only regular whose disappearance was explained on-screen was Kam Fong, whose character Chin Ho Kelly was killed off in the final episode of Season 10.
McGarrett's middle initial is "J," but it is never said what it stands for (Season 5's "Death is a Company Policy"). He jokingly says in Season 7's "A Gun for McGarrett"that his middle name is Aloysius.
Jack Lord, a resident of Beverly Hills, was asked to audition for the show, and in less than a week was cast, had flown to Hawaii and started filming. This quick chain of events would lead to him becoming a prominent figure in Hawaii, contributing to many local causes and charities, and being posthumously honored in his adoptive state with a statue.
In inner city neighborhoods, "Five-0" is one of the many slang terms used in reference to the police. "Five-0" is also the slang term for the Ford 302 engine optioned in the Ford Mustang automobile. In the photography world, "Five-0" is the slang term for a 50mm focal-length lens (also called a Nifty Fifty), and two mid-2000s era DSLR cameras, the Nikon D50 and Canon 50D.
Following the death of Leonard Freeman in 1974, Jack Lord stepped in his shoes and ran most of the production for the remainder of the series, although he was never credited. From 1974-1980, he shared ownership with the Freeman estate. Lord nearly walked off the series in 1974, following a despite with CBS.