didn't know certain cast changes had taken place.

For example, when I was a kid and I started watching "Married...with Children," I started somewhere in season five with Jefferson as Marcy's husband. I still remember watching the pilot episode for the first time and seeing Steve and asking my dad who that was. When he replied "Marcy's husband," I asked "just for this episode?" he then said "No, he stays for a while" or something to that affect.

I don't think it was until the first season DVD came out for "Mama's Family" that I realized Bubba wasn't there from the beginning. So I must have only seen the syndicated episodes as a kid.

Another one was "Cheers." Now I wasn't a regular viewer until it came to Nick at Nite but I remember as a kid thinking Woody was there from the beginning. I had heard my dad mention one of the actors had died, but I was unaware that Woody came on as a replacement.

I did't start watching "Ellen" until mid season 2 so I didn't realize that season 1 was actually called "These Friends of Mine". I remember when ABC aired these episodes in repeats, it was odd seeing the different cast members and theme song not to mention seeing Ellen with longer hair.

I didn't start watching "Hangin' with Mr. Cooper" until season 2 when it moved to T.G.I.F. so I didn't realize Nicole and Geneva weren't always there. I didn't realize this until reruns of season 1 starting airing, then it got me all confused.

I also started with MWC with Jefferson as the husband and discovering Steve in the repeats.

Not sure if Saturday morning shows count or not, but here goes.

I remember watching Pee-Wee's Playhouse on CBS when I was around 3 or 4, and I was unaware of the first season, when they had a small set, and a different cast (including Phil Hartman as Captain Carl).

It wasn't until I saw episodes from the Hi-Tops Video series that I finally saw the show as it was originally in 1986. The first season was shot in a converted loft on 480 Broadway in SoHo, the artist capital of New York City.

http://www.imdb.com/title/tt0090500/faq

back in the 60s I used to watch PETTICOAT JUNCTION all the time but I started watching in the 66-67 season. It wasn't until I started watching reruns of the early episodes after it was canceled that I saw that some cast members were different at first.

The Incredible Hulk only seen certain parts of the show I did watched some show I own then all on dvd.

magnum pi I never watched the begin of it I remember catching the pilot on TV couple years ago,
the middle I never watched the being of it
what would you do? I never seen the being of it

back in the 60s I used to watch PETTICOAT JUNCTION all the time but I started watching in the 66-67 season. It wasn't until I started watching reruns of the early episodes after it was canceled that I saw that some cast members were different at first.
I first discovered PJ in the 90s when it aired on TV Land as part of "Hooterville Saturday". It wasn't until years later that I knew about the black and white episodes, which I actually like better than the color episodes.

Night Court, didn't realize there was so much turnover until the syndicated repeats.

Friends
Mad About You
Frasier
George Lopez Show
The Big Bang Theory
Duck Dynasty
The King Of Queens
Yes Dear

I never knew there were black-and-white episodes of BEWITCHED until Nick at Nite started showing them in the 90s, same with MY 3 SONS.

I never knew there were black-and-white episodes of BEWITCHED until Nick at Nite started showing them in the 90s, same with MY 3 SONS.
I was the same way with Bewitched, I Dream of Jeannie, & Gilligan's Island.

I was the same way with Bewitched, I Dream of Jeannie, & Gilligan's Island.
Same here with Petticoat Junction added. Bewitched I was surprised there was a different Gladys Kravitz and Louise Tate. Syndication only ran the color seasons, Petticoat I only seen the episodes with Meredith MacRae and Lori Saunders.

Friends
Mad About You
Frasier
George Lopez Show
The Big Bang Theory
Duck Dynasty
The King Of Queens
Yes Dear

What significant cast changes took place on any of those shows?