Rollin learns how to remove a straitjacket. Usually, the technique doesn't require to be able to dislocate one's shoulders, as legend has it, in order to gain the slack necessary to pull an arm out of the sleeves. Straitjacket escape is one of the most sensational and famous magicians' tricks; it was a staple in illusionist Harry Houdini's act.
The set for "The Happening" nightclub is a redressed version of the same set where Spock is attacked in Operation -- Annihilate! (1967). Both shows were filmed at Desilu (Paramount) around the same time and both aired in April 1967.
Dan Briggs's black, white, and shades of gray apartment color scheme was a deliberate choice by executive producer Bruce Geller. The apartment was sometimes referred to off-camera as the 'black-and-white room'.