This was Al Harrington's first appearance as Ben. He had appeared in previous episodes in different roles, but this was his first as a regular character.
This episode (and season) mark the first significant changes in the opening theme song and the accompanying visuals. The song has been re-recorded and sounds noticeably different. Moreover, some of the original opening theme shots have been replaced. The original shots all came from either the 1968 pilot episode (e.g., the luau dancing girl and smiling musician, Zulu crashing into a bad guy) or were shot by Reza Badiyi specifically for the opening theme. Now, several shots from Season 4 and Season 5 episodes have been substituted (James MacArthur looking through a shattered car window, Kam Fong using a walkie talkie on a rooftop, a flaming car wreck, and new cast member Al Harrington hopping a fence). Also, as Zulu was no longer part of the cast, his shot was removed.
Angie mentions to Ben about the dirt on Hotel Street. Hotel Street is the "redlight" district of Honolulu.
This episode (and season) marks the beginning of a slight format change in the show: Instead of opening with a teaser of several minutes' duration (during which the "crime of the week" gets set up) before the opening theme song rolls, Season 5 begins episodes with the opening theme song up front, followed by the teaser and first act pushed together with no break in between. Note that the teaser is still effectively part of the script as written, leading to the strange situation where each episode's title suddenly appears onscreen several minutes into the running action (i.e. at the official start of Act I).
On McGarrett's transcripts his father's occupation is listed as a plumber and the address of his business is 4024 Radford Ave. That's the CBS Studios address.