American sit-com set in Italy.
To Rome With Love
There was a hot “Italian” babe in that series along with the American cast. Funny they don’t mention her. 
Good call, I remember that show. I had three older sisters who insisted we watch that every week. We only had one TV set, so I was outvoted and had to sit through each sickeningly sweet episode.
I am definitely thinking of Six O’Clock Follies; the station (TV, I think) was the Armed Forces Radio Network’s station. “Five O’Clock Follies” was the real-life term used to describe the actual Army press briefings (one of which included the infamous line, “We had to destroy the village in order to save it”) that took place in Saigon. I think the show used “Six O’Clock Follies” to refer to the station’s 6 PM news broadcasts.
Actually, that was Major Bonacelli’s second (and final) appearance; Hans Conreid played him the first time.
Conreid was also on ***Gilligan’s Island ***as the aviator Wrong Way Feldman.
Well that throws a spanner in the works. I would have thought they were already there. I mean if not, then where?
I think there might be a continuity problem in The Flintstones. 
Depending on the definition of sitcom, Lillyhammer would qualify. It is more comedy than anything else, though it’s a hour long.
Valerie Bertinelli had a short-lived sitcom called Cafe Americain, set in Paris.
How about It’s About Time? Two astronauts end up stuck on prehistoric Earth when they travel faster than the speed of light.
Midway through the series they returned back to modern times.
See pp. 16 and 19.
Darn. I looked through but didn’t even see it.
Would Lost in Space count?
How about Daktari, set in Africa?
Nope, there was at least one episode where Will ended up back on Earth.
Huh. I was going to point out to bunyupp that Daktari wasn’t a sitcom, but apparently I’m okay with Lost in Space being one…
On Earth okay, but was it in America? (It’s been awhile since I’ve seen the series.)
I sort of remembering going back in time to what was apparently the US.
Also in the not intended to be a sitcom category was Land of the Giants. They started in space, but there may have been some earth scenes.
Only unintentionally, and even then it was terrible! 
Excluding the opening and closing scenes, The Love Boat! Fantasy Island. Okay, they were both hour-long, but I hesitate to call either one a drama.
“Oh the pain, the pain.”