One curious thing about this episode is that in other episodes the territory covered by the 87th Precinct appears to be mostly working class but apparently the 87th has some well-to-do sections as evidenced by the King home.
Carella: How would you like to join the force, Mr. King?
King: It doesn't pay enough, Mr. Carella.
King: Well, whadda we do now?
Carella: I guess we do what the man said.
King: I thought I've seen all kinds.
Carella: Stick around. Score's only the beginning.
Carella (to King): I'm not here to make moral judgments. I'm here to get the kid back.
King: I'm a man fighting for his life.
Diane: You're a man about to commit murder.
King: A bunch of crooks. Why should I play by their rules?
Cassidy (over the phone): Enough with those Hopalong wisecracks.
Cy: Tell them not to call the cops it's the first thing they do.
Carella: Do we understand each other, Mr. King?
King: We understand each other, Mr. Caretta.
King: I don't have to proceed on any assumption, Caretta.
Kathy: You kidnapped him?
Eddie: That's the way it looks, Kathy.
The set for the King house would be used again two episodes later in Killer's Choice.
John Astin would later go onto star in The Addams Family.
Anthony Carbone is billed as Tony Carbone in the credits.
This episode is based on the novel of the same name by Ed McBain.
Future First Lady Nancy Reagan is billed as Nancy Davis, her maiden name, in the credits.
Famed Japanese director Akiro Kurasawa based his acclaimed 1963 film High and Low on the same novel on which this episode is based.