[5] On July 7, 2020, it was reported that Lenkov was fired from his role as executive producer and showrunner on MacGyver and Magnum P.I, following an investigation into allegations that he created a toxic work environment.

[16] Despite solid viewership during its first season and the ability to hold its own against powerhouses like ESPN's NFL Monday Night Football and ABC's Castle, Five-0 wasn't pulling the same ratings as CBS's flagship police procedural, NCIS.

As such, Peter Lenkov outlined that the second season would have a lot more to it, promising new cast members and an expanded setting, stating, "...we wanted to explore the other islands, and I think we just never got the chance.

"[17] But an even bigger surprise came two months later on August 18, 2011, just prior to the 2nd season premiere, when NCIS: Los Angeles star Daniela Ruah tweeted, "Aloha hoaloha!

Shortly after the news was confirmed, however, Ruah tweeted that it was a one-time crossover and that she would be coming back to her regular show[18][19] while NCIS producer Shane Brennan mused "Interestingly, Daniela has never been to Hawaii, so it took no convincing," Brennan also stated that the visit to the show wasn't gratuitous and would have a purpose, jokingly adding, "I'm a bit concerned they might not give her back!

"[21] The two-part episode, titled "Pa Make Loa (Touch of Death)", drew big ratings for both shows.

[24][23] NCIS producer Shane Brennan remarked that the reaction with fans and critics seemed largely positive and added "Crossovers are not easy to pull off when you're working in the same town, and when you've got the other show being shot a five-hour flight away, it's particularly challenging.

[27] In the episode, MacGyver and the Phoenix Foundation travel to Northern California to track down a copycat serial murderer who has been mimicking San Francisco's infamous Zodiac Killer.

[29] This plot thread continued into Five-0, with the episode, "Hahai i na pilikua nui (Hunting Monsters)"[30] in which Chin Ho Kelly follows up on Dalton's tip-off, telling McGarrett "that call from your friends at the Phoenix Foundation wasn't wrong".

[31] After this set-up, Five-0 actors Daniel Dae Kim, Grace Park, and Taylor Wily crossed over into the MacGyver episode "Flashlight".

In the episode, The Phoenix Foundation is sent to Oahu to help the Hawaii Police Department and Five-0 with rescue and recovery efforts and ends up working closely with Chin Ho Kelly and Kono.

Immediately, fans speculated on whether this meant that Garcia was coming to MacGyver and reprising his role as Jerry Ortega or as a completely new character.

CBS would later confirm that Garcia was going to reprise his role as Jerry in the 5th season with a Tweet which read, "Anyone call for a conspiracy theorist?

"[38] Other actors, such as Henry Ian Cusick, Corbin Bernsen, Lance Gross, Elisabeth Röhm, Patrick Monahan, Andre Reed, and Janel Parrish have played various characters in the different series, also causing continuity issues that were not addressed.

The series focuses on a fictional state police task force, known as "Five-0" led by Steve McGarrett, that is set up by the Hawaiian governor to fight major crimes in Hawaii including murder, kidnapping, and terrorism.

[47] An additional television score from Hawaii Five-0, featuring music written for the series by Brian Tyler and Keith Power was released in July 2023.

[71][72] Names of original Five-O cast members and characters although changed but non-gender swapped serve as the namesake for rebooted Five-0 characters, actors Richard Denning and Danny Kamekona from the original Five-O serve as the namesake for Governor Richard Denning and confidential informant Kamekona Tupuola in the reboot; while characters Doc Bergman and Che Fong serve as the namesake for Max Bergman and Charlie Fong, respectively, in the reboot..

Although not officially portrayed by the original actor who played the original Steve McGarrett, Jack Lord appeared in a seventh season episode of the reboot as an unnamed character; the episode replicated the appearance of Lord by using CGI effects along with a body and voice double.

[78] Ed Asner portrayed August March in the 1968 Five-O and also reprised his role in the second and third seasons of the rebooted series.

During the second season episode "Ka Hakaka Maikaʻi", Daniela Ruah made a guest appearance as her NCIS: LA character Kensi Blye.

Joe White calls in Agent Kensi Blye from NCIS: Los Angeles Office to review the video of John McGarrett, Governor Jameson, and Wo Fat for Steve, but only recognizes the word "Shelburne".

Agents Sam Hanna and G. Callen of NCIS: Los Angeles are called in to assist Five-0 finding a suspect, Dracul Comescu.

Later, Callen and Sam must return to Los Angeles to stop a possible smallpox outbreak from becoming a reality with Danny "Danno" Williams and Chin Ho Kelly coming along to help.

The Phoenix Foundation team of MacGyver gets rerouted to Hawaii after a 7.2 magnitude earthquake hits the coast of Hawai'i Island.

While aiding Detective Chin Ho Kelly and Officer Kono Kalakaua from Five-0 task force, they also have to deal with the Chinese intelligence soldiers who use the earthquake to steal top-secret weaponry that the scientists are currently developing.

Soon after, Junior Reigns is kidnapped as leverage for the criminals to get the list back, leading to Magnum's team helping Tani Rey and Quinn Liu in a search-and-rescue mission.

Also, Noelani enlists the help from Quinn when she suspects that her uncle did not die of a heart attack and thinks it was a murder cover up.