According to Chaney biographer Don Smith, the actor was drinking during rehearsals of the show and damaged props which had to be replaced. When the show was actually shot, an inebriated Chaney was under the impression that it was a dress rehearsal and gingerly laid the furniture down instead of throwing it as he should. He can be heard saying "Save for the show" when he uncharacteristically lays down a chair.
Lon Chaney Jr. previously played Frankenstein's Monster in The Ghost of Frankenstein (1942). He also played Larry Talbot / the Wolf Man in four other featuring the character: Frankenstein Meets the Wolf Man (1943), House of Frankenstein (1944), House of Dracula (1945) and Abbott and Costello Meet Frankenstein (1948).
Contrary to his biographer's claim, Lon Chaney Jr. was not intoxicated when he played the Frankenstein monster in this broadcast. In a later interview, Chaney explained what really happened. Before the broadcast, he had spent four hours in the makeup chair, having his monster makeup applied. When the performance started, Chaney assumed it was only a dress rehearsal. In the broadcast (which is available on YouTube), Chaney is handed a chair - but instead of smashing it, he sets it down, and shouts "Break! Break!" while making smashing motions with his hands. Following this scene, the director informed Chaney offscreen that the broadcast was happening live, so in subsequent scenes, Chaney didn't hold back and freely broke pieces of the set. (In the YouTube video of the broadcast, he falls out a window and later smashes Dr. Frankenstein's lab equipment.)