This episode was prolific character actor Ed Lauter's debut.
Mannix's telephones are push-button models while Carol Barr's phone is a rotary model. At that time, the phone companies were moving from analog rotary phones to digital touch tone phones. In most areas businesses were the first to get touch tone phones, although it was phased in geographically. Some push button phones could send either a tone signal or a rotary pulse signal for dialing in order to accommodate customers during the transition. It would be almost two decades before digital touch tone dialing would become the standard for the telephone industry.
The camera used by Carol Barr is a Nikon F with FTn Photomic prism and F36 motor drive. The Nikon branding has been obscured.