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. Since Australia is one day ahead of the United States, they were essentially born on the same day.
This show premiered on September 20, 2010, forty-two years to the day from the premiere of Hawaii Five-O (1968).
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).
When the show premiered in 2010, the character of Kono Kalakaua (Grace Park) was written to be a rookie cop in her mid-twenties. Park was 36 years old when the show premiered. Her character is supposed to be younger than Steve McGarrett (Alex O'Loughlin). In real life, Park is two years older than O'Loughlin.
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.