It should surprise precisely nobody that Matthew Weiner is very, very careful about the correct current events in Mad Men, even including what play Don and Megan went to see.
(Also cute: the modern Hare Krishna movement — more formally known as the International Society for Krishna Consciousness, or ISKCON — was founded in New York in 1966, just months before the last night’s Christmastime episode.)
Update: It gets deeper. I’m informed via the Well that:
The diner Crane and Kinsey meet in at the end of the episode is identifiably Ratner’s, which happens to be just down the street from an actual ISKCON storefront on 2nd Avenue.
Mohawk was hit by a strike in December of 1966, which lasted until the end of January.