Plot hole: McGarrett is hunting for heroin dealers who've laced the drug with arsenic. Yet when he and Chin Ho arrest Harry Parch and find his stash, McGarrett performs the TV cop cliché of sticking his finger into the white powder and tasting it. Even that small a dose of arsenic could be lethal, and seasoned cop that he is, McGarrett would know that.
Plot hole: Nadira hides from the bad guy behind a screen - with her feet in plain view. Then, after capturing her, the bad guy inexplicably lets her go, even though her knowledge poses a danger to him. Given that he's killed without a qualm before, this makes no sense at all.
Add timeJean G
Plot hole: 8-22 "Love Thy Neighbor, Take His Wife": McGarrett has two unexplained clairvoyant moments in this episode. First, he divines that the Indian-style headband is turquoise without seeing it. Then, after the kidnappers' phone call proves untraceable, he somehow knows that it was made from a specific pay phone.
Add timeJean G
Plot hole: As a security test, McGarrett secretly has several dummy bombs planted in the court building, then later shows the governor where they are. Each time he pulls one of the devices from its hiding place, citizens in the courthouse stroll casually by without so much as glancing at the loudly-ticking "bomb." No one knew about the test, so McGarrett's bombs should be attracting some attention, if not causing outright panic.