Bob's Packers jersey is a much newer version than the version of the late '70s.
When Donna tells Eric she disagrees with her parents vows, a contemporary takeout coffee cup is visible behind her, on the shelf above the washing machine. In the next shot, it's gone.
When Fez is playing Twister by himself behind the couch and calls out, "right leg, green", he is trying to place his left leg.