Joan cuts her finger deeply during New Years Eve with Greg, requiring stitches. Yet 2-3 days later at the partners meeting, she has no bandage nor any sign of injury.
The pattern of fresh paint on Anna's wall changes between consecutive shots.
When Don first arrives at his office he hands his coat and hat to his secretary, but both are already hung up when he steps inside.
The imported Japanese monster film, Gamera, had not been released until after the date that the episode was set.