Jack Lord is the only actor to appear in all 281 episodes.

The "Five-O" in the series' title pertains to Hawaii as the fiftieth state to enter the union (August 21, 1959), even though the "O" in the title is not the number zero (0). The meaning is the same. In the 2010 series, the "0" in the title is the number zero (0). Over the years, the term "five-O" has become a slang term meaning any police officer. For example, in New Jack City (1991), Ice-T's undercover character is outed by another character, who uses the expression, "Yo! Five-O! This guy's a cop!"

Hawaii is the only state that has never had a state police agency.

Jack Lord lived in Beverly Hills when he was asked at the last minute to read for the part of McGarrett. He read for it on Wednesday, flew to Hawaii on Friday, and was in front of the cameras the following Monday. He later became a permanent resident, and prominent figure in Hawaii, contributing to many local causes and charities, and often mentioned publicly in consideration for political office. After he died, a fan-funded bust of him was erected in Honolulu.

Kam Fong, who played Det. Chin Ho Kelley, was a real-life Honolulu Police officer from 1946 to 1962, when he retired for a career in real estate.

McGarrett's office was in Iolani Palace, the actual palace used by the last Kings and Queens of Hawaii. In 1969, the Palace had fallen into disrepair after years of abuse and neglect. it has since been restored, and the palace can now be toured for twenty dollars.

Even though Khigh Dhiegh made fifteen appearances as archvillain Wo Fat, Dhiegh and Jack Lord only appeared on-screen together (in the same scene) four times, including the pilot and the series finale.

Jack Lord was the only cast member to stay with the series during its entire twelve-year run. Zulu , the first of the regular cast to depart the show, left in the fourth season. Kam Fong left after the tenth season. James MacArthur left the series after season eleven. 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.

The opening montage consists of: a breaking wave (from the film Surfari (1967)), a hula dancer (Helen Torco), the "Lady Columbia" statue at the National Cemetery of the Pacific, model Elizabeth Logue running down the beach, a close-up of Ms. Logue from a side view, thirteen-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, the Aloha Tower, Honolulu, and the Ilikai Hotel.

The hula dancer in the opening montage is Helen Torco, in an uncredited role. Known professionally as Helen Kuoha-Turco, she was later a professor at Windward Community College. She had a credited role in an episode of Hawaii Five-0 (2010). Until 2015, those were Torco's only acting credits.

Magnum, P.I. (1980) began production soon after this series wrapped its last episode. Early episodes included references to this show, but a plan to have Jack Lord appear as McGarrett never came to pass.

McGarrett was a Navy Intelligence officer, with the rank of Lieutenant Commander, before he became head of Five-O. He ostensibly remained in the U.S. Navy Reserves throughout the series, occasionally recalled to active duty to assist the Navy or Coast Guard on special cases.

In many early episodes, whenever someone pulled up outside the Iolani Palace, there was a red 1967 Camaro parked nearby.

The name Wo Fat came from a restaurant in downtown Honolulu.

McGarrett was a Korean War veteran.

Following the death of Leonard Freeman in 1974, Jack Lord stepped into Freeman's shoes and ran most of the production for the remainder of the series, although he was never credited on-screen as a producer. This was by agreement from 1974-1980, in exchange for Lord's shared ownership, with the Freeman estate, of episodes produced between Freeman's January 1974 death and the end of the series in 1980. Prior to this agreement, Lord nearly walked off the series in 1974, after a dispute with CBS.

This was the longest-running crime show in television history until Law & Order (1990)'s thirteenth season in 2002. It can be considered the second-longest running crime show, if Gunsmoke (1955) isn't considered a crime show. Law & Order: Special Victims Unit (1999) hit its thirteenth season in 2011, and Law & Order (1990) ran for twenty years, so it could also be considered the third-longest running crime show.

The name Chin Ho came from Chinn Ho, the owner of the Ilikai Hotel, which is where the penthouse shot of Jack Lord in the opening title sequence was taken.

For the ninth season, the Five-O offices moved out of the Iolani Palace and into an office building down the street, partly because the Iolani Palace was getting a facelift, and partly because 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 filmed in the office building, which was introduced in each episode that season by showing the Iolani Palace with scaffolding over its facing, 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. They moved back for the tenth season.

Jack Lord was not in a key shoot-out scene because it was filmed on a Saturday, and, according to the producers during a special feature in season two of the new 2010 series, Jack Lord, contractually, never worked on Saturdays.

During his 1973 Aloha From Hawaii live concert, Elvis Presley cited Jack Lord as one of his favorite actors, thanks to his performance in this show.

While McGarrett was usually called McGarrett or Mr. McGarrett, his official police rank equivalent was Captain.

Danny was the only member of the Five-O ever shown smoking cigarettes. Chin smoked a pipe in several episodes.

McGarrett often referred to Kono as "Big Kanaka".

Al Harrington and Herman Wedemeyer appeared in different roles on the show before assuming the roles of Ben and Duke respectively. Wedemeyer was in the first episode, playing Honolulu Police Lieutenant Balta.

Duke's given name is Edward.

While the offices were portrayed as being at the Iolani Palace, the office interiors were sets on a soundstage.

Steve, Danny, Chin, and Duke all endured suspensions from Five-O during the series. Danny and Steve were the only characters ever charged with murder.

The syndicate that Tony Alika headed was called "Kumu".

Government Intelligence Chief Jonathan Kaye was played by six different actors: James Gregory, Joseph Sirola, Lyle Bettger, Bill Edwards, Tim O'Connor, and Robert Dixon.

Was recently voted one of the best TV theme songs ever.

Richard Denning, who had recently retired to Hawaii, came out of retirement to play The Governor.

McGarrett sometimes called Chin Ho "Fatso".

In the first season, the closing credits showed a police motorcycle racing through Waikiki. From the second season on, it show the famous outrigger canoe being paddled off Diamond Head.

The phone number for ~Hawaii Five - O~ is 808-732-5577 as shown on Kono's Card in the Episode "Nightmare Road"

Peggy Ryan, who played McGarrett's second secretary, Jenny Sherman, also appeared as the Governor's secretary, Mildred, in two first season episodes.

Kam Fong had originally auditioned for the part of Wo Fat.

Gregory Peck was offered the lead role of McGarrett. He turned it down.

Richard Boone was Leonard Freeman's first choice to play McGarrett. Boone already lived in Hawaii, but he turned down the role.

Some music scores came from The Wild Wild West (1965).

Duke Lukela first appeared as a Honolulu Police Department Sergeant, before becoming a Hawaii Five-O investigator.

McGarrett often called his first secretary, May, "Love".

Besides Intelligence Chief Jonathan Kaye, other recurring characters include Police Officer Sandy Welles, Doctor Grant Ormsbee, and hang glider pilot Molly Taggart.

Other than Wo Fat, other notable adversaries for McGarrett that appeared in more than one episode included mob bosses Honore Vaschon and Tony Alika, pimp Big Chicken, and the Robin Hood-like Lewis Avery Filer.

Before joining Five-O, Danny attended the University of Hawaii, and then transferred to the University of California, where he graduated with a degree in Criminology.

McGarrett has a sister who lives in California.

This show is the first to portray the use of a CB radio. Hawaii Five-O: Tiger by the Tail (1968) to be exact.

Mad Magazine once did a spoof of Hawaii Five O called "How-Are-Ya Five O".

Elizabeth Logue is the actress who appears as the girl in the opening credits

Whenever someone from Five-0 showed up at Tony Alika's house, his usual greeting was "Welcome to my little grass shack".

Several actors played different roles in various episodes before becoming recurring cast members.

According to Stuart Whitman, Leonard Freeman had first offered him the role of McGarrett. They were working on the series "Cimarron Strip" (1967), where Whitman also served as an executive producer. Freeman really wanted Whitman for the role, but with Whitman's commitment to the western, he declined.

The opening title sequence was created by television director Reza S. Badiyi. In the October 18, 2010 issue of TV Guide, the show's opening title sequence ranked No. 4 on a list of TV's top 10 credits sequences, as selected by readers.

Chin Ho smoked a pipe.

In many American inner city neighborhoods, "Five-O" is one of the many slang terms for the police. "Five-0" (spelled differently, sounds the same) is also a slang term for the Ford 302 engine option in the Ford Mustang automobile. In the photography world, "Five-0" is slang for a 50mm focal-length lens (also called a Nifty Fifty), and two mid-2000s era DSLR cameras, the Nikon D50 and Canon 50D.

Dr. Bishop (Jean Tarrant) was often consulted by McGarrett on cases where he was dealing with someone who was mentally unstable. She ran the state mental hospital.

McGarrett's office was blown up twice during the series. The first time it was blown up by Mr. Savage in "A Gun for McGarrett". The second time by Victor Jovanko in "Blood Money is Hard to Wash". Both times it was done by sending a bomb in a fake award for McGarrett.

The show was satirized in Mad Magazine as "How Are Ya Five-O".

Richard Denning, who portrayed the Governor throughout the run of the original series, also appeared in a 1956 movie with executive producer and creator Leonard Freeman's wife, Rose Freeman, who was professionally known as Joan Taylor when she was an actress. The name of the film was Girls in Prison (1956). Denning portrayed a clergyman, and Taylor portrayed one of the film's inmates.

Five-O's office telephone number, 732-5577, as stated by McGarrett in the episode "Blind Tiger" and shown on Kono's card in the episode "Nightmare Road," was actually the number for Hawaii Five-O Studios on Diamond Head Road in Honolulu.

Lee Stetson and Bruce Boxleitner both acted on this programme but not together. In 1983 Bruce Boxleitner played Lee Stetson in Scarecrow and Mrs King.

The theme for Hawaii Five has links to The year2000 Australian documentary-comedy The Dish. Background: The Dish is the nickname for the radio antenna in the town of Parkes which received the pictures of the 1969 Moon landing sent by Apollo 11. The narrative had the U.S. Ambassador and a NASA technician at a country dance. It being a semi-official occasion the rock-band of local youths was instructed to play the Ausralian and American National Anthems. The boys were so unfamiliar with the U.S. anthem they ended up playing the Hawaii Five-O theme by mistake.

Jack Lord played Paul Burke's brother Preston in a second season episode of 12 O'Clock High (1964).

Another actor that was considered for the role of McGarrett was Robert Brown.

McGarrett finally caught Wo Fat in the series finale. However, at the end of the episode, Wo Fat digs into his boot and takes out a file, leaving open the possibility of a reunion.

McGarrett actually caught Wo Fat in one encounter. He was forced to give up Wo Fat, because the Chinese government wanted him back, in exchange for a downed U2 pilot.

It was disclosed in season four, episode twenty-one, "Good Night, Baby - Time to Die!", that McGarrett had been hired by the Governor in 1959, immediately upon Hawaii's creation as the fiftieth state, as head of Five-O, and that McGarrett took no vacation time off between 1959 and 1968, when McGarrett "was tired", and visited Switzerland to rest.

In the episode the blue lady wo fat(khigh dhiegh)uses women as drug mules this episode was remade in 2015 wo fat(mark decascos)uses women as drug mules