I know it's one of those movies they ocassionally put back in theaters

Not occasionally - very regularly. I'm not sure of the actual numbers but it was something like two or three times a decade.

eta: I lied. Once a decade.

Gone with the Wind was given theatrical re-releases in 1947, 1954, 1961, 1967 (in a widescreen version),[20] 1971, 1989, and 1998. It made its television debut on the HBO cable network in June 1976, and its broadcast debut the following November on the NBC network, where it became at that time the highest-rated television program ever presented on a single network, watched by 47.5 percent of the households in America, and 65 percent of television viewers.

Maybe on TV...Mom's a little older than Sally and I think that's where she saw it(And it's trippy to type that Mom's older than Sally Draper, cause I am too. Cause she's eight right now.) But mom may have been older...memories have a way of telescoping and stuff.ETA: Or yeah, Hec, maybe it was such a favorite of Betty's she took Sally to the re-release, even though it seems Sally's a bit young for it.

Gone with the Wind was given theatrical re-releases in 1947, 1954, 1961

Well, there you go. The daughter could've easily seen it in 1961.

ETA: I missed Erika's ETA.

Oh, I have a question: did Betty's riding breeches seem period? I mean - were there stretch fabrics then?

Oh, yes. All knits have stretch and I'm sure riding breeches were made out of some kind of knit material. They just didn't have lycra and the like which allows non-knit fabrics to stretch.

Plus, they are so fanatical about being period, down to the year of the typewriters, I doubt they'd disregard something like the breeches.

Equestrian teams at the Olympics - 64, 96 and 68

To me, it just seems like the switch to stretch breeches was later in the '60s.

Shoooooooooooowshowshowshowshowshow.

Oh my, how I love this tiny little horrible narrow world in the shiny box.

I realized about halfway through that if 14 months have gone by, Peggy's child is exactly the same age as mine. Huh.

Did anyone else catch the featurette after the end? It was mostly pointless, but there was one line in it "Nah, Draper knocked her up" (right after Pete's "fat farm" comment) that must have been cut from the opening conference room scene.

I thought that was in the episode.

yes, definitely in the episode.