The water tower and shed on Jubal Foster's farm are the very same structures that were the water tower and chicken coop on the Flint farm in "Ellie Saves a Female." The only difference is that in the first season, all camera angles were from the water tower side of the barn and in this second season episode all the camera angles were from the opposite end of the barn.
Everett Sloane guest stars as Jubal Foster. He also wrote the lyrics to "The Fishin' Hole," the theme song of The Andy Griffith Show, although the lyrics were never performed on the show.
The episode title is a reference to the political thriller Keeper of the Flame (1942), starring Katharine Hepburn covered by a reporter played by Spencer Tracy.
The first of four times that Barney gets gassed.