Plot hole: Vinton demonstrates the intercom with the instruction to push a button to talk but throughout the episode, they listen in on each other. This would not be possible if the person (s) being listening on is not holding the button to activate the mike.
Mama's Family (1983)
1 mistake in Now Hear This
Starring: Ken Berry, Allan Kayser, Dorothy Lyman, Vicki Lawrence
Genres: Comedy
Naomi Oates Harper: Sonja, honey, did your mama ever talk to you about boys?
Sonja Harper: Well, she told me never to marry a locksmith.