When Matthew the butler pumps the last few bullets into the monster, the gun is pointed into the groin area.
A confused Chaney, reportedly thinking he was at a dress rehearsal and unaware that he was live, sets some expensive-looking furniture down gingerly and only mimics throwing it saying aloud, "Save it for the show."
While Frankenstein is talking to his wife and later while the announcer is talking, the sound of stagehands cleaning up the lab set can be heard.
Just as the camera cuts to the announcer, an off-stage hand can be seen pulling away from his face.
Chaney's monster breaks BOTH ends of the prop wire before he is "electrocuted" by its current.