* AlternateCharacterInterpretation: Steve [=McGarrett=] tends to [[JackBauerInterrogationTechnique treat suspects]] like potential threats to national security, especially during the first season, whereas [[ByTheBookCop Danny]] follows protocol. They've toned it down over the years. People speculated that he treated them as such because he was reeling over his father's murder. In "Ina Paha", the AlternateUniverse episode where his father is alive, Steve, still in the Navy, is still stern but more reasonable. He doesn't start asking Victor questions until [[CowboyCop Danny]] convinces him.
* {{Anvilicious}}: "Puka 'ana" is all about fighting sex trafficking.
* BigLippedAlligatorMoment: The infamous [[https://www.youtube.com/watch?v=oQYwFND7rHE Subway product placement]], which stops the show for a full minute to have the characters sing praise to how cheap, delicious, and healthy Subway sandwiches are.
* CompleteMonster: See [[Monster/{{Bellisarioverse}} here]].
* CreatorsPet:
** Lori is definitely ''not'' a fan favorite. She was eventually PutOnABus.
** Catherine has also become one in Seasons 3 and 4 due to taking a lot of screen time away from other characters, which has led to quite a bit of backlash from fans as well. She was also Put on a Bus, but eventually TheBusCameBack for her. How well this is going to go with the audience remains to be seen but considering the massive amounts of hate she used to get she might not stay for long.
* CryForTheDevil:
** [[spoiler:Wo Fat turns out to have been raised by Doris, but she had to abandon him.]]
** Near the end of Season 6, [[spoiler: Gabriel Waincroft dies from cardiac arrest.]]
* DiagnosedByTheAudience: Max is introduced by the governor with the line "They say he's a savant" and had to fire his piano tuner because he liked to chat and Max found it "emotionally draining". In his off time he investigates cold cases and makes pickles, but doesn't trust phones or watch the news because it's scary. This suggests that he might be on the spectrum.
* EnsembleDarkHorse
** August March is only in two episodes, but is a popular RoguesGallery member for his manipulative tricks and how his actor is reprising a role from the original series.
** Serial arsonist Jason Duclair only appears four times, but greatly intrigues many fans through a combination of his terrifying pyromania and occasional NobleDemon moments.
** Retired [=FBI=] profiler Alicia Brown is only in six episodes but is one of Steve's more popular love interests.
** OneShotCharacter mob hitman Nick Mercer has a surprisingly big following due to [[spoiler:his FanficFuel rich BackStory as TheAtoner who has been faking the deaths of his recent targets and setting them up in new lives with his own UndergroundRailroad.]]
** StrugglingSingleMother and grieving sister Amanda Chase (played by Creator/SarahHabel) from "Helu Pu" is one of the best-regarded victim's relatives from the show.
** It's only in Season 7 that Duke gets a PromotionToOpeningTitles, but his role as a MauveShirt CoolOldGuy who is played by a star of the original show makes him extremely popular.
** Gerard Hirsch only makes a few appearances per season after his debut, but his role as a reformed criminal with a goofy crush on Kono makes him pretty popular.
* FanPreferredCouple: Steve/Danny, aka [[PortmanteauCoupleName McDanno]], despite Steve having dated Catherine and Danny getting back together with his ex-wife, Rachel. The sheer amount of fanfiction, communities, and board threads devoted to them are staggering.
* GeniusBonus: In "Ho'ohuli Na'au", Steve and Danny are given a photography book the VictimOfTheWeek published. The cover is an exact match to a photography book Creator/ScottCaan (Danny) published a year before Hawaii Five-0 started.
* HarsherInHindsight:
** Though this was aired on the same day Amanda Berry was freed after being held captive for a decade, Season 3's "Ho'opio" involved another girl named Amanda being held captive for 10 years. Except [[DownerBeginning it wasn't as happy]] [[VictimOfTheWeek an ending]] as the Cleveland case.
** Danny's occasional mention of Steve's aneurism face turns into this once we learn that [[spoiler: Kono's mom suffered one a while ago and now sits in a wheelchair, unable to speak.]]
** In the infamous Subway scene, the obese man mentions Jared Fogle as a reason to lose weight with Subway.
** The main victim "Makaukau 'ce e Pa'ani?" who died with a note pinned on his body that he was a criminal hits hard in the Philippines following President Rodrigo Duterte's elevation as president, as Duterte was known to encourage extrajudicial killings of suspected criminals by rogue police and private citizen posses, and a hallmark of these executions was notes on the victims' bodies naming their crimes. Many of those killed have later been proven to be innocent of the crimes they were accused of. One of the most prominent victims is Maria Aurora Moynihan, the daughter of ex-Baron Moynihan and sister of Philippine actress Maritoni Fernandez.
** In the first season, Kono makes a comment about Chin's wife-to-be, Malia, abandoning him when he needed it most and is rather bitter about it even though [[spoiler:it was Chin breaking up with Malia to [[ItsNotYouItsMyEnemies protect her]]]]. Much later in the series, [[spoiler:Malia and Kono are put in SadisticChoice that Chin can only save one of -- and he chooses Kono, even if it utterly breaks his heart that he had to lose Malia over it.]]
* SugarWiki/HeReallyCanAct: To the surprise of many viewers, Music/NickJonas did a pretty good turn as [[spoiler:sociopathic cyber-terrorist]] Ian Wright in "Akanahe."
* HilariousInHindsight: Here, Creator/MykeltiWilliamson played Clay Maxwell, Grover's former partner in Chicago, a suspected DirtyCop. A year later, he would play Denny Woods, another dirty cop in ''Series/{{Chicago|PD}}'', no less.
* JerkassWoobie: Danno certainly has plenty of moments where he comes off as a bit of a self-righteous prick, but his life is hardly a bed of roses. The whole mess with Rachel aside, he's had his little brother betray him to run from the FBI, said little brother kidnapped for a ransom of 18 million that he found and delivered only to find that Matt was already dead. Then his new girlfriend turns out to be in the run from an abusive husband which almost kills him. That is, of course, not before he is thrown into a Colombian prison where a cop is even worse off than in an American one. Not to mention that Rachel lied to him about the pregnancy and only tells him he has a son when said son turns out to be deadly sick. [[spoiler: Don't forget the time he and Steve were attacked up in the air while undercover as drug shipment pilots. Danny is forced to break cover when Steve gets shot in the liver in order to receive instructions on how to land the plane. Steve lives thanks to a transplant from Danny, who, unlike Steve, [[DudeWheresMyRespect gets no get-well-soon cards or any form of praise]]]]. Yeah, he hasn't had it easy either.
* LikeYouWouldReallyDoIt: [[spoiler: Kill off Steve [=McGarrett=] in the Season 6 finale "O Ke Ali'I Wale No Ka'u Makemake"]].
* MoralEventHorizon: Ian Wright proves that he is [[NotSoHarmlessVillain more than just a typical hacker]] by holding over 300 people on a plane hostage and willing to send them to their deaths if they don't let him go. He further sinks to this when [[spoiler: he kidnaps Grover's daughter and forces Grover to steal 100 million dollars for him]]. [[EvenEvilHasStandards Even Wo Fat is so disgusted]], [[spoiler: that he just puts a bullet in him and helped release Grover's daughter]].
* {{Narm}}:
** In "He Kane Hewa'ole", Five-0 finds a cardboard box with a human head in it. [[SpecialEffectsFailure A very, very fake human head.]]
** Some of the product placement is among the most blatant on TV. In some instances, it can lead to a BigLippedAlligatorMoment where characters take a few minutes to extoll the virtues of Subway, just barely managing not to roll their eyes, but other times it occurs during plot-relevant situations.
** If the episode decides it's time for a dramatic fistfight, all the usual combat rules fly out the window, both combatants become implausibly MadeOfIron as the two beat the utter hell out of eachother and throw eachother onto just about every destructible object in the room if not multiple rooms, and allies that were potentially right behind the hero inexplicably disappear to let the fight rage on unabated. For most series, this would be RuleOfCool and RuleOfDrama alike for a climactic final battle. For ''Hawaii Five-0'', this is every serious bad guy that isn't meant to be shot or a pushover.
** A late season 8 episode has Steve find out that [[spoiler:Joe White]] has been captured thanks to Junior giving him classified information about it from the operation setup over phone. Two ''fighter jet'' transitions later implying he used his connections to get a fast ticket over, and Steve walks right up to the group at nighttime to immediately force his way into the op in a way that is so sudden it comes off as surreal rather than serious.
* NightmareFuel: [[AntiHero Steve]] has a lot of leeway with his Five-O team to get the job done, and this includes allowing for his CowboyCop antics to an extent. Despite three separate governors attempting to reign him in, their own immunity clauses for him typically mean he can get away with antics like ''using a live grenade to blow open a sealed store door'', before he even has an official warrant to act on. It's not the legality of his actions, [[TheMcCoy Danny will always dispute that]], it's the sheer, unstoppable warpath Steve will make the moment he knows what he's gunning for, and the amount of bodies likely to be left in his wake if it comes to a fight.
* ParanoiaFuel: [[spoiler: Wo Fat]] has a habit of rigging claymore mines on people's cars, which will detonate once the ignition slot is keyed.
* RetroactiveRecognition: Many won't recognize but Kamekona's actor Taylor Willy participated as ''Teila Tuli'' in UFC 1 in the first UFC bout ever as a representative of Sumo.
** Gabriel's actor Christopher Sean would later voice Kazuda Xiono in ''WesternAnimation/StarWarsResistance''.
* SpecialEffectsFailure:
** Unfortunate example in the third season premiere, when [[spoiler:the helicopter airlifts away the (moving) armored truck carrying Wo Fat.]] Ruins an otherwise perfect SugarWiki/MomentOfAwesome. Compare that with the much more technically ambitious, [[SugarWiki/MomentOfAwesome completely [=CGI=] free plane-lift scene from]] ''Film/TheDarkKnightRises''. Let's just say that if your CG effort at a smaller-scale version of this looks like a video game cutscene, you are DEFINITELY doing something wrong.
** In Season 9's "Aia i Hi'ikua; i Hi'ialo," a propeller plane lands on an aircraft carrier in the opening. Shots of the action on the deck alternate between stock footage, serviceable CGI for a TV budget, and rather bad blue-screening.
* StoicWoobie: [[spoiler:Chin]] takes the fall of his uncle's embezzlement and ends up being disgraced from HPD, disowned by his cop-pride family, and separated with his fiancee. He trades his house's deed for cash to essentially bribe HPD to stop further investigation.
* TheyWastedAPerfectlyGoodPlot: The crossover with ''Series/NCISLosAngeles'' notably lacks [=McGarrett=]'s involvement, meaning there's no interaction between former Navy [=SEALs=] Hanna & [=McGarrett=], or the respective bromances of Danny[=/=]Steve & Callen[=/=]Hanna.
* TheWoobie:
** Malia, Chin's ex-fiance. We meet her in He Kane Hewa'ole, and from everything we've heard about her from Kono and what we know about what happened to Chin, it's expected that she's the kind of lady who was willing to dump him after he was disgraced. Instead Malia is a nice lady who loves Chin, was the one dumped for her own protection, and she still wears her wedding ring on a chain around her neck. She tries to be nice to Kono who hates her, and she's so awkward around them both... Poor lady.
** Steve probably counts as an IronWoobie. His mother dies in a car accident when he's a teenager, and instead of banding together as a family, John [=McGarrett=] sends Steve and Mary away to their relatives on the mainland. Steve becomes estranged from his father and his sister (the latter of which probably counts as a Woobie, too), but he grows up to be a strong-willed {{Determinator}} without the guidance of his family. And then the series starts, and Steve gets to hear his father's murder over the phone, thousands of miles away and with no way to help. And ''then'' Steve discovers that the car accident that killed his mother wasn't an accident, and that his father sent them away to protect the two of them while he searched for answers. And after all of that, it turns out that [[spoiler:his mother was alive the whole time, but was in hiding after faking her own death to keep her family safe.]] Not only that, but [[spoiler:she is still keeping secrets, disappears and reappears without notice, and in general is still keeping Steve LockedOutOfTheLoop.]] This is on top of all the other crap that gets thrown at him, like having former brother-in-arms betray him, having his former commanding officer and mentor jerk him around, and discovering that [[spoiler:his father's friend, the governor, was working with the an who had ordered his parents' executions.]] Danno often complains that Steve needs professional help, but with a backstory like that, it's honestly a wonder that he didn't turn out worse.
----