Factual error: At the party in the second half of the episode Don Draper is seen filming indoors with a movie camera without floodlamps. The movie film of that era would have required much more light. And the camera would have made significant noise and require periodic winding, which did not happen.
Factual error: Don brings home Sally a new dog for her birthday at the end of the episode. Clearly an oversight considering the girth of the wide muzzle and "blockier" forehead of the dog. This presumably leads the informed viewer to surmise that the dog is a British Golden Retriever, a far fetched tale considering the lack of communication between European and American dog breeders during the cold war era. Taking this assumption one step further, the cream colour of the coat is also an indication of a later time period, as the cream colour was only introduced in the past twenty (20) years for British sub-genus.