Emily:
Ruth McDevitt and her character name issues are resolved once and for all in this episode as she finally appears with the name which most fans recognize her by "Miss Emily Cowles." Previously she appeared in episode #1 as an unnamed elderly woman who has written to the paper's advise columnist "Miss Emily", and later in episode #5 as "Edith Cowles".

Alex Grasshoff directs his second of three episodes with "Bad Medicine", the others were #2 "The Zombie" and #10 "The Energy Eater".

Captain Joe Baker:
Actor Ramon Bieri who plays "Capt. Baker" appears again in episode #17 "Legacy Of Terror" again cast as a police captain only here he's called "Capt. Webster."

The Indian (Diablero):
Actor Richard Kiel joins the Kolchak monster club with back to back appearances here in "Bad Medicine" as "Diablero" and in the next episode #9 "The Spanish Moss Murders" as "Peremalfait".

The other actors with two "monsters" each are Craig Baxley and Mickey Gilbert.

In Syndication this episode was sometimes called "The Diablero"

Carl: (opening narration) F. Scott Fitzgerald once wrote, 'The rich are different than you and me.' They sure are. They got more money. But there wasn't enough money in the world to save some members of Chicago's upper crust from a fiendish force so dark, it can only be called diabolic.

Obnoxious Staffer: Quality...I could have shot that better with shoebox and a pinhole! To think I stayed here all night to develop...that!
Carl: Why don't you stay a little longer and develop a personality?

Malloy (the auctioneer): And your name is, sir?
Carl: Kol…worth. Carl Kolworth.
Malloy (the auctioneer): Any relation to the Woolworths?
Carl: Distantly, yes. They dealt in wool, we dealt in coal.

The "dead" dog on the floor of the gem exchange is seen moving before the camera cuts away.

The Joliet State College of Barbering
Described in the context of an ex-con, Carl is undoubtedly referring to the Indiana State Prison at Joliet. Like most correctional facilities, it provided vocational training in the hope that inmates with skills wouldn't return to a life of crime. Presumably, Al Delgado learned barbering there.