When playing Scrabble, the play passed from Midge to Red, who was on her right. By the rules, play should have passed to her left (to Kitty).
During the party, Eric says, "I'm not a doctor, but I play one on TV." This phrase originated from a commercial that first aired in 1986, while the episode takes place in 1979.
The Old Milwaukee beer cans are not the right type of cans for 1977. The cans shown are from at least a decade later.