Rather belatedly, tonight Darling Husband and I watched "Mad Men" for the first time (we have DVR). Loved it, but there was a howler that really bugs me. A character mentions that Dick Nixon is campaigning for president, and one of his rivals is John Kennedy. So that means it's 1960; and judging by the light clothing it's maybe midyear.
But then there's a close-up of one of the secretaries typing on an IBM Selectric--which wasn't introduced until 1961. It took me all of 30 seconds to research that on Google. Couldn't the set designer have done the same?