Here are some interesting facts:

John was the only actor to make it all the way from the first pilot to the final episode and the only one to appear in every Three's Company episode.

Terri was the only roommate who never did an episode with the Ropers, while all five roommates starred with Furley.

Larry was the only one who guest starred on both Three's a Crowd and The Ropers.

Both Jenilee Harrison and Suzanne Somers would later work shows with Patrick Duffy (Dallas and Step By Step)

Percilla Barnes, who played Terri, was one of the people who the year before auditioned for the Cindy Snow charachter Jenilee Harrison played.

Norman Fell would reunite with John Ritter in a guest appearance on Hooperman and Richard Kline and Don Knotts would guest star on Suzanne's Step By Step.

Originally posted by chrisw79
Here are some interesting facts:

John was the only actor to make it all the way from the first pilot to the final episode and the only one to appear in every Three's Company episode.



At first, I wondered what episode Janet (Joyce DeWitt) missed, but now I know that it was Stanley's Hotline in season 3, where Jack's girlfriend Linda replace Janet for one episode.

Does anybody know why Joyce DeWitt missed this episode?

Also, what is rather ironic with that episode is that how would Linda by explained to Mr. Roper without him finding out that she was Jack's girlfriend and therefore, was a straight man?

A couple more:
Of the five roommates, the only parent we never saw was Cindy's mother.

There was an episode where Janet was helping Furley's nephew where a reference to the film The Graduate was made where Jack called Janet Mrs. Robinson. That movie featured Norman Fell.

Audra Lindley, Ann Wedgeworth, and Jordan Charney were all on the soap opera Another World at the same time. Audra starred on the show as Liz Matthews from 1964-1969, Ann Wedgeworth played Lahoma Vane Lucas from 1967-1970, and Jordan played Sam Lucas from 1967-1970 and again in 1974. In fact, Lahoma and Sam were lovers on the show, and, due to the show's popularity, they were spun-off onto Somerset, on which both Jordan and Ann starred from 1970-1973.

Around 1988, Suzanne Somers, Jenilee Harrison, and Don Knotts all appeared in an episode of She's the Sheriff (which Somers was the star of). The episode set up the premise for a possible spin-off named Mr. Moe's.

Priscilla Barnes was originally signed to play the lead in She's the Sheriff; however, she quit after a contract dispute. Suzanne Somers was then contacted to take over the part.

Originally posted by stella
Does anybody know why Joyce DeWitt missed this episode?

She was having problems regarding her salary. ABC had promised her a pay raise; however, they decided to take it away from her because they were already making plans to give Audra Lindley and Norman Fell pay raises once they moved to The Ropers. Joyce met with the president of ABC and, rightly so, her raise was re-instated.