Factual error: Don, who professes to be a Buddhist, chants in the jail cell and refers to Buddha as "god." Adherents to this religion do not worship the Buddha and never refer to him as god. Later on, Don chants to Krishna, a Hindu deity not even remotely connected with Buddhism. So, just what is Don - a Buddhist or a Krishna?
Visible crew/equipment: 8-16 "Legacy of Terror": As an HPD cop escorts the old man out of McGarrett's office, he trips over a camera cable and nearly falls. When the actor recovers his footing and finishes his exit, the cast regulars simply pretend it never happened and go on with the scene.
Character mistake: After distracting the guards, Danno tosses a grappling hook onto a ledge and climbs the side of the building. He then goes about his business, carelessly leaving the hook and rope dangling from the ledge for all to see. For a seasoned 5-0 team member, that's pretty sloppy covert operations.