First appearance of Mr. Bickley.
The disgruntled customer is holding an ABBA album. The cover art is instantly recognizable. The AB has been pasted over leaving BA as the name on the front side but the back side still says ABBA.
The opening scene shows Mork reading a Superman comic book and writing an angry letter to Superman. The movie Superman (1978) premiered one month before this episode aired, and starred Christopher Reeve in the title role. Christopher Reeve and Robin Williams were roommates at Julliard in the early 70s and remained very good friends for the rest of their lives.