When Pete is telling Don that Duck will be the new president of Sterling Cooper, Don's tie changes position multiple times, even though Don is sitting still and not moving.
When Betty takes a drink, we see from her profile that she's holding a cigarette in her right hand, but when the camera cuts to a frontal shot, her hand is empty and the cigarette is resting in the ashtray.
When Betty tells the doctor she can't have a baby, he replies by telling her there are other options, but those are for young girls. He is obviously talking about abortion. No reputable doctor in 1963 would even consider that option let alone talk about it so calmly. Abortion was illegal in 1963, a fact the writers obviously forgot.