These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Sean Winston after he began to make threats to shoot a child in a hostage situation.
Critical Research Failure: A few things in "Ua Hopu". For instance, Interpol having a worldwide tactical team in Osaka, Japan. Which doesn't work since Interpol is a collection of police agencies working together by sharing intelligence. Although Interpol does have a tactical team responsible for protecting Interpol facilities in France.
Same thing with the uniforms of Japanese police officers. Although the basics are correct (e.g. vest, cap, shirt), the shoulder patches and the kanji for the vests are incorrect. In the episode, the kanji is portrayed as "特別警察官", which means "Special police officer" in Japanese. Although it's correct, all Japanese police officers have vests with the kanji "警察庁;", which means "National Police Agency". And don't get me started on the Osaka Police crime scene investigators.
In "A ia la aku" (for the first episode filmed in Hong Kong), the sedan Kono and Adam rode in has mainland Chinese plates, when it's stipulated by Hong Kong laws that mainland-based vehicles should have Hong Kong plates affixed at the front and back in order to be admitted into Hong Kong territory. Also in "Kupuʻeu", the sedan Kono and Adam use is LHD, despite having the correct Hong Kong license plates on.
All of 3.20. There is no chance an Naval Intel Officer (Catherine) has the kind of training to keep up with a SEAL (Steve).
Fan-Preferred Couple: Steve/Danny. The sheer amount of fanfiction, communities, and board threads devoted to them are staggering.
"Funny Aneurysm" Moment: Even 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 it wasn't as happyan ending as the Cleveland case.
He Really Can Act: To the surprise of many viewers, Nick Jonas did a pretty good turn as sociopathic cyber-terrorist Ian Wright in "Akanahe."
He's Just Hiding: What McGarrett suspects is going on with his father's murderer, terrorist Victor Hesse, after shooting him off a cargo ship. He orders the Coast Guard to try to find his body. They haven't, but insist they'll keep looking. 'Course, it turns out McGarrett was justified in his caution.
Danno: Rachel, just hear me out. Before you sic your lawyers on me, I wanna remind you of something. I moved 5,000 miles so that I could see Grace twice a week. Twice a week, okay? That is 48 hours, 52 times a year for a grand total of 2,500 hours. When you factor in sleep, and school, I can really only count on 400 hours of real face time each year. And ya know? That's only going to shrink as she starts making friends... Then she goes off to college... So ultimately that does not leave me with a lot of time to spend with my daughter. Not as much as I would want. But I never complained. I never complained. Because every single one of those minutes reminds me of what I am doing, and why I am here. That little girl is my life. So I am asking you- I am begging you to please- please just be kind. Don't take her away from me, that's all.
What an Idiot: The Yakuza boss forgets to clear his fingerprints off the stolen Champ box and throws it in the dumpster outside his own bar — leaving just enough clues tying him to the kidnapping that Five-0 can arrest him.
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.
Stoic Woobie: 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.