Gunsmoke is referenced in this installment. A character claims to have served as a deputy under Matt Dillon in Austin, Texas, and Paladin calls the character on it, by stating that Matt Dillon was never marshal in Austin.
Bernard Herrmann was long associated with CBS, and wrote the network a library of cues. One of the pleasures of watching CBS shows from the '50s and '60s is recognizing these. In "The Protégé", Sprague expires to a cue reminiscent of Herrmann's music for "Journey to the Center of the Earth".