Alex O'Loughlin and Scott Caan were born just a day apart. Alex in Canberra, Australian Capital Territory (A.C.T), Australia, and Scott in Los Angeles, California. Though with Australia being one day ahead of the United States, they were practically born on the same day.

Terry O'Quinn (Joe White), Daniel Dae Kim (Chin Ho Kelly), Jorge Garcia (Jerry Ortega), and Henry Ian Cusick appeared on Lost (2004).

When this show premiered in 2010, the character of Kono Kalakaua (Grace Park) was written to be a rookie cop in her mid twenties. Park was thirty-six-years-old when the show premiered. Her character is supposed to be younger than Steve McGarrett (Alex O'Loughlin). In real-life, Grace Park is two years older than Alex O'Loughlin.

This show premiered on September 20, 2010, forty-two years to the day from the premiere of Hawaii Five-O (1968).

As of season five, Daniel Dae Kim (Chin Ho Kelly) is the only cast member to appear in every episode.

During the opening credits, the camera zooms in on McGarrett (Alex O'Loughlin) standing on a balcony. It is the same balcony, on the same building, on which McGarrett (Jack Lord) was standing during the opening credits of Hawaii Five-O (1968).

James MacArthur, who originated the role of Danny "Danno" Williams on Hawaii Five-O (1968), was scheduled to make a guest appearance during the first season. Unfortunately, he died before he was able to make an appearance.

When CBS announced this series for the fall of 2010, they released the opening credits from the pilot online. They featured an electric guitar version of the classic theme, and it was met with positive results. Producers revealed they hadn't decided whether or not to use it on a permanent basis, so they decided to stay with the classic. They brought in a full orchestra to re-record it, and three of the members had even played on the original. The electric guitar rendition of the Hawaii Five-O theme song was later used on promotional advertisements.

Due to the several crossovers between them, the series is set in the same universe as JAG (1995), NCIS (2003), NCIS: Los Angeles (2009), NCIS: New Orleans (2014), Scorpion (2014), MacGyver (2016), and Magnum P.I. (2018).

On this show, Chin (Daniel Dae Kim) and Kono (Grace Park) are first cousins. However, in Hawaii Five-O (1968), the two were not related.

In August 2010, Scott Caan injured his knee while filming a stunt for the show, and tore an ACL. The injury was written into the show.

Daniel Dae Kim was the first person cast. He was followed by Alex O'Loughlin, Grace Park, and then Scott Caan.

Dennis Chun, the son of the original Chin Ho Kelly, Kam Fong, has a recurring role as HPD Sergeant Duke Lukela. The role of Duke is also a tribute or reference to Herman Wedemeyer, who played Duke in the original series. Dennis Chun also had roles on Hawaii Five-O (1968), as three different, unrelated characters, in three different episodes, one during season six, and two during season seven.

In Hawaii Five-O (1968), Five-O's offices were purported to be on the second floor of the I'olani Palace, which, in the late 1960s to early 1970s, was a state office building, but has since been restored as a royal residence museum. Five-O's offices for this series are depicted as being in Alii'olani Hale (right across the street), a state office building of similar architecture built in the 1870s, which houses Hawaii's Supreme Court.

During season two of this series, McGarrett's Chevrolet Silverado Crew Cab truck is shown with license plate number "F6-3958", a nod to Hawaii Five-O (1968), where Jack Lord's McGarrett had this plate number for his personal state issued car, used for the 1968 Park Lane and the 1974 Marquis Brougham.

Grace Park plays Kono, a role originally played by Zulu. This marks the second time she has starred in a re-imagined television series, playing a role originated by a man, the first being Boomer from Battlestar Galactica (2004), a role played on Battlestar Galactica (1978) by Herbert Jefferson, Jr.

The Five-O name comes from Steve's father. When he and his sister were kids, Steve's father used to call them Five-Oers, because Hawaii is the 50th U.S. state.

Al Harrington, who played Detective Ben Kokua on Hawaii Five-O (1968), has a recurring role as Mamo Kahike on this show.

On this show, Danny Williams got his nickname from his daughter Grace, who called him "Danno", because she could not pronounce "Daniel" (or Daddy, by inference) when she was learning to speak. On Hawaii Five-O (1968), no reason was specifically given for why Danny's nickname was Danno, and he did not have a daughter.

Robert Loggia, Clyde Kusatsu, Patty Duke, Al Harrington, George Takei, Edward Asner, Don Stroud, Dennis Chun, and Jimmy Borges appeared on the new and original versions of Hawaii Five-O. Asner is interesting in that he reprised his character from the original series, art thief "August March".

On this show, Steve's middle name is Jack, in honor of Jack Lord, who played Steve McGarrett on Hawaii Five-O (1968), while on the original series, Steve's middle name was "Aloysius" (pronounced AL-oh-wish-uss).

The title of the original series, Hawaii Five-O (1968), and that of the updated series, Hawaii Five-0 (2010), are pronounced the same: "Hawaii Five-Oh". However, they are spelled differently. The former uses the capital letter "O" as a pronunciation spelling for the number zero. The latter uses the numeral "0" instead.

There are at least eighteen actors and actresses throughout this show that have also played on Lost (2004).

The wife of the original series Creator, Leonard Freeman (who died in 1974, age fifty-three), was Joan Taylor (known after her marriage by her given first name, Rose, along with her husband's family name, Freeman, making her Rose Freeman), died on March 4, 2012. After her death, she was the dedicatee "In Loving Memory Of Rose Freeman" on the March 19, 2012 broadcast of this show.

CBS wanted to bring the series back one year sooner for the 2009-2010 season, with Edward Allen Bernero in charge of production. The plot would have been a sequel with Steve McGarrett, Jr. taking over the unit from Steve McGarrett, Sr. It didn't go beyond the scripting stage. In 2009, Alex Kurtzman and Roberto Orci took over, and decided to reboot the series, instead of make it a sequel to the original.

Michael Shanks auditioned for the role of Daniel "Danno" Williams.

Richard T. Jones, as the second Governor, Sam Denning, succeeded Jean Smart, the first Governor, Pat Jameson. Both roles are a reference or tribute to the role of Governor Paul Jameson, and the actor who played him for the entire run of Hawaii Five-O (1968), Richard Denning.

After seven seasons, Daniel Dae Kim and Grace Park quit over salary disputes.

Terry O'Quinn plays recurring character Commander Joe White, who was McGarrett's instructor at S.E.A.L.s School. O'Quinn previously played Captain Boone, a "CAG" (for Commander, Air Group, the senior pilot aboard any aircraft carrier) in JAG (1995). JAG (1995), NCIS (2003), and this show are all linked by crossing characters.

Danny's favorite team is the New York Jets, and when he moved to Hawaii he adopted the University of Hawaii's football team as his favorite college team, due to the similar color scheme to the Jets' uniforms.

What seems like a mistake regarding the ranks of the team, is actually a nod to McGarrett's military service with the Navy S.E.A.L.s. In the S.E.A.L.s, and other Special Forces units, rank is not as important as experience and expertise, so a lower ranking member could be team leader. In cases where the highest ranking member is team leader, the rest of the team is usually free to make suggestions and plans, acting almost as a pseudo democracy, with the team leader making the final call as to what they do. A good example of this is Lone Survivor (2013), during the scene in which the team argues over what to do with the goat herders who discover them, and American Sniper (2014), when Chris Kyle asks to start his own task force, and when he joins the Marines for house clearing, despite his assignment being to provide cover fire as a sniper.

Throughout the series "Kalakaua Avenue" is mentioned (Steve and Danny have chased people on Kalakaua Avenue). Kalakaua is Kono's last name

On this show, season two, episode nineteen, "Kalele", Edward Asner played a jeweler called August March. He played the same character on Hawaii Five-O (1968), season eight, episode fifteen, "Wooden Model of a Rat". The new episode used footage of his original appearance, explaining in the new continuity that he was arrested in his youth by a cop named McGarrett (Steve's father). Asner played March again on this show, season three, episode two, "Kanalua".

Leonard Freeman, the producer of Hawaii Five-O (1968), named Wo Fat after a now-defunct restaurant in Honolulu's Chinatown. The Wo Fat building remains on the National Register of Historic Places.

Scott Caan's and Alex O'Loughlin's birthdays are one day apart. August 23 and 24, 1976, respectively.

General Motors provided the motor vehicles for this show during the first four seasons. Beginning in season five, the contract with GM was cancelled since two of the leading roles (Chin Ho and McGarrett) drove vintage Ford vehicles (Chin with a 1966 Mustang coupe, and McGarrett with a 1974 Mercury Marquis Brougham). This also affected the Honolulu P.D. squads used throughout the series, the Impala 9C1 after the 2013 model year (based on the previous 1996-2013 model sold as the Impala Limited, which was phased out in 2016) was only sold to fleets or rental car agencies. Also, the 2011-present Chevrolet Caprice PPV (which is the replacement for the Impala 9C1) is not sold to the general public, hence the production crew using the Impala for the squads.

This is the second attempt to remake Hawaii Five-O (1968) (this time, successfully). The first had been the sequel Hawaii Five-O (1997), which featured Grace Park's Romeo Must Die (2000) co-star Russell Wong.

The car the group is seen driving around in is a 2010 or 2011 Camaro LT with a V6 engine, the RS performance package, and police lights added to the front end. McGarrett is seen numerous times driving the Camaro, although it's Danno's car. GM's Chevrolet Division is the motor vehicle provider. On Hawaii Five-O (1968), Ford Motor Company was the provider, with Ford Division and Mercury Division vehicles being used by Five-O personnel. However, the lead vehicle was always Jack Lord McGarrett's Mercury. For most of the first seven seasons of Hawaii Five-O (1968), Steve's car was a black on black (sometimes referred to as "triple black") 1968 Mercury Parklane Brougham four-door. The Park Lane was last used during the eleventh season of Hawaii Five-O (1968), where it sat in a warehouse for several years, the Park Lane sedan used in the early seasons was restored, and now is in the hands of a Chicago, Illinois resident. After season eight, McGarrett drove a 1974 Mercury Marquis Brougham hardtop sedan, and after Hawaii Five-O (1968) ended its run in 1980, Jack Lord gave the Marquis to his stunt double, John Boley Nordlum. On this show, that same car make, model, and color, 1974 Mercury, is shown being stored in the garage of Steve's house, and Steve explains to Danno that his father had been restoring the old Mercury before he was kidnapped. This is a tribute to the famous car McGarrett used in the later seasons of Hawaii Five-O (1968).

During the opening credits (seasons one to six), the Hawaiian Airlines jetliner seen is an Airbus A330-200. Hawaiian Airlines signed a 4.4 billion dollar Memorandum of Agreement with Airbus in 2007, where the A330s have been used in place of their existing Boeing 767s for non-stop flights to the U.S. East Coast. The 767s in service will be retired after 2015 - three 767s were sold off to United Airlines (the previous airline sponsor of the classic series). Hawaiian Airlines was in the process of procuring the Airbus A330NEO (New Engine Option) but entered into a nonbinding agreement with Boeing where the airline ordered the 787-9 with an option to order 10 more.

William Sadler (John McGarrett) and Alex O'Loughlin (Steve McGarrett) appeared in August Rush (2007).

The HPD lab technician "Charlie Fong", introduced late in season one, is based on the character "Che Fong" on Hawaii Five-O (1968). This also holds true with Lori Weston (introduced in season two), named similarly to Sharon Farrell's character (Lori Wilson) during season twelve of Hawaii Five-O (1968), and Max Bergman (introduced in season one, recurring in season two, but with on-screen credit for every episode in season two of this show), who was based on the character of Doc Bergman, as played by Al Eben on Hawaii Five-O (1968), although he was sometimes simply credited as either "Doc" or "Coroner" in fifty-one episodes, beginning with the fourth season, and he also portrayed three other characters before the fourth season, two of those were also doctors.

On Hawaii Five-O (1968), Kono and Governor Jameson were male.

David Keith and Keith David had roles on this show.

Scott Caan and Chi McBride appeared in Gone in 60 Seconds (2000).

The Mercury Marquis was used on Hawaii Five-O (1968), and is owned by Steve McGarrett on this show.

Several references to the Star Trek franchise (from the original series, spin-offs, and feature films with the original series and spin-off cast including) have been featured throughout the series. During season two, Dr. Max Bergman's (Masi Oka's) VW 181 has a "Warp 9" personalized license plate, while in season three, George Takei guest starred as Chin's uncle (Takei appeared on Hawaii Five-O (1968) back in 1975 during season eight). Also, Dr. Bergman's feud with Dr. Dhawan was over a Yeoman Janice Rand action figure, which was revealed during season five. Supporting cast member Terry O'Quinn (Joe White) appeared on a Star Trek spin-off as a Starfleet Admiral, and during season seven, Rosalind Chao (Keiko Ishakawa O'Brien from Star Trek: Deep Space Nine (1993) and Star Trek: The Next Generation (1987)) as the Governor of Hawaii. Daniel Dae Kim appeared on Star Trek: Voyager (1995) and Star Trek: Enterprise (2001), and writers Roberto Orci and producer Alex Kurtzman (who are part of the Kelvin timeline Star Trek film series). Kurtzman is also the co-creator of Star Trek: Discovery, the most recent Star Trek TV series, set in the Original timeline. Also, Peter Weller (who guest starred in Star Trek: Enterprise (2001) and Star Trek: Into Darkness (2013) as Admiral Alexander Marcus) has directed some of this show, including, season three, episode fifteen, "Hookman".

Anna Belknap, A.J. Buckley, and Melina Kanakaredes are people who appeared on CSI: NY (2004), and have guest-starred on this show after CSI: NY (2004) ended.

The character of Wo Fat, the principal archvillain of both Hawaii Five-O (1968) (as portrayed by Khigh Dhiegh) and this show (as portrayed by Mark Dacascos), appeared just eleven times (in thirteen episodes, as some were two-parters) in Hawaii Five-O (1968), over the course of twelve years and two hundred seventy-nine episodes, including the pilot, and the series finale, titled "Woe to Wo Fat". On this show, Wo Fat was also introduced in the pilot, but has already appeared in nine episodes, up to, and including the third season premiere.

In season two, episode eighteen, "Lekio", the old man on the boat is played by James Caan, Scott Caan's real-life father.

In season two, episode eighteen, "Lekio", Tony Archer was played by James Caan, Scott Caan's (Detective Daniel "Danno" Williams') real-life father.

William Sadler, who portrays Steve's father, John McGarrett, and Christine Lahti, who portrays Steve's mother, Doris McGarrett, were both born in April 1950, Sadler on April 13, 1950, and Lahti on April 4, 1950, just nine days apart.

In season five, episode six, "Ho'oma'ike", Kamekona's last name is revealed to be Tupuola. It appeared in a school yearbook that the own Kamekona is watching to help Chin Ho Kelly on an old murder investigation that happened when Kamekona was student.

John McGarrett's tomb reads, "March 15, 1942 - September 20, 2010". His date of death not only matches with the release of the first episode, but also with the 42nd Anniversary of the premiere of Hawaii Five-O (1968).

In season three, episode fifteen, "Hookman", they pay homage to RoboCop (1987), played by Peter Weller, who is the special guest star of the show. In the gun store scene, on the wall is the same modified Beretta machine pistol RoboCop shoots. In fact, Weller was the director for the episode as well.

During the opening of the show, just before the wave appears, if you freeze the video you will see the zip code for the city of Honolulu appearing on the bottom of the screen. There is also a red triange on the center right of the screen. This coincides with the zip+4 postal designation for the building highlited

Danny went to Seton Hall University, and he minored in Economics.

Many actors and actresses who appeared in Hawaii Five-O (1968) appear in the rebooted version Hawaii Five-0 (2010).

Guest stars Cary-Hiroyuki Tagawa, Mark Dacascos, and Ian Anthony Dale have starred in video game based movies and web series. In Mortal Kombat: Legacy (2011) Cary reprised his role as Shang Tsung from Mortal Kombat (1995), Ian played Scorpion and Mark played Kung Lao. In another video game based movie Tekken (2010) Cary and Ian played father and son Heihachi and Kazuya Mishima. Cary also played Heihachi in Tekken: Kazuya's Revenge (2014).

Scott Caan and Terry O'Quinn appeared together in the 2001 film American Outlaws .

In season four, episode seventeen, "Ma Lalo o ka 'ili", Danno (Scott Caan) is forced to mediate between his parents to prevent Clara from presenting divorce papers to Eddie. Eddie and Clara Williams are played by Tom Berenger and Melanie Griffith respectively. This is the second time that they worked together, after Shadow of Doubt (1998).

In Season Nine, Scott Caan has voluntary decided to have less screen-time , so that he could spend time with his family in Los Angeles.

Chin Ho was originally dismissed from the Honolulu Police Department after being falsely accused of taking bribes. Steve chose him for the task force, because he didn't believe the accusations, and because Chin Ho was his father's former partner. It is later revealed in the latter half of season one, that Chin's uncle was the one who was involved (to pay off medical bills where Chin became a fall guy who took the blame, where he was protecting his extended family) which resulted in his reinstatement to HPD as a Lieutenant.

Alex O'Laughlin (McGarrett) took a leave of absence during the second season so that he could enter into treatment for addiction to pain killers. This was explained by having Steve take off on a secret mission without telling anyone where he was.

Dennis Chun (Sgt. Duke Lukela) has now appeared on all 4 past and present shows Magnum P.I. (1980) and (2019) as the same character and Hawaii Five-0 (1968) and (2010).