After Kelly leaves, Frasier is sitting at the restaurant table talking to Martin and Daphne. When the shot swaps back and forth from different camera angles, one of the wine glasses on the table switches from being full of yellow wine to being empty and back again several times.
Frasier appreciatively says he is enjoying a "warm Poire William," while holding a snifter with a brown liquid. Poire Williams is a colorless brandy.
Frasier prides himself on his honesty, and Daphne says she's never known him to tell a lie, but during his angry defense to everyone he claims he stole Kelly away from a professional football player when in fact she was already breaking up with him when she met Frasier.