Per the title, an All Points Bulletin (A.P.B.) is a broadcast issued from one law enforcement agency to another containing information about a wanted suspect who is to be arrested or a person of interest, whom law enforcement officers are to look for such as a fugitive or missing person.
Both David Janssen, i.e. Dr. Kimble, and Paul Richards, playing Neil Pinkerton, died of natural causes at relatively young ages: 48 and 50, respectively.
This is the second of three appearances Lou Antonio makes in the series. While each appearance is as a different character, each of the three characters he portrays is an outlaw of some sort. The other two episodes are See Hollywood and Die (1963) and The Devil's Disciples (1966).
This is the second of three appearances Shirley Knight makes in the series, each appearance as a different character. The other two episodes are The Homecoming (1964) and Echo of a Nightmare (1966).