A candle alternates from lit / unlit as Karen waits for her massage.
When Karen is sitting at the desk, with a fistful of pencils, the pencils often change position in her hand.
Amount of tassels in the bowl as Grace pretends to cry in front of the Landlord.
When Will is sorting his CDs, Grace enters the flat and puts her bag on the sofa, and there is no design on the bag, it is all black. When Will gives Grace a glass of wine, there is a flower design on the bag.
When Will and Grace play a board game, the red plastic cards on the board change their position many times, as does the paper money and the dice.