Three's Company (1977)

Strange Bedfellows - S2-E4

Continuity mistake: When Mr. Roper tries to explain to the girls and his wife what he was doing in Jack's bedroom, watch over Mr. Roper's left shoulder on the shelf. The number of yellow cans on the shelf keep alternating between one and two cans throughout several minutes. In addition, also notice the suitcase on the floor under the shelf as well. Whenever one yellow can is shown, the suitcase is by itself and whenever two yellow cans are shown, there is a square silver bag in front of the suitcase.

Stanley Roper: I want my rent.
Helen Roper: Stanley, where are your manners? You're supposed to say hello when you walk into a room.
Stanley Roper: Hello, I want my rent.

Trivia: Once the first season with Terri started, Cindy no longer had "Snow" mentioned as her last name for the remainder of the episodes she was in (possibly due to the fact that this was the first season that started without Suzanne Somers completely and the producers wanted to retire the "Snow" surname altogether).

Show generally

Question: During the first three seasons, all the main cast appeared in every episode (except one without Joyce Dewitt by season 3), but it seems once Suzanne Somers left the show, episodes had some cast members absent on a regular basis (mainly Richard Kline and Don Knotts who both only appeared in selected episodes in the later seasons). Was it a sudden budget cut or another reason for this?