About halfway through the episode Horizontal Hold, Arthur is eating dinner with Frank Sinatras ex-lover. She and Arthur have clear glasses with a brown liquid (iced tea?) on the table. Doug and Carrie come home and Arthur gets up to tell Doug to get rid of his date. When Arthur returns to the table there are 2 coffee mugs in place of the glasses. No one went into the kitchen, and the date is still eating. Someone forgot what they were drinking out of.