Continuity mistake: When Will and Grace apologize to each other in the break room, after Grace finishes her apology she hugs Will. In this shot all her hair is behind her right shoulder. In the next shot most of it is in front of her shoulder. (00:18:35)
Continuity mistake: When we see Karen nursing Jack when he is ill, Jack puts down a soup bowl on the side table. A few shots later the spoon in the bowl is in a different position. (00:07:30)
Continuity mistake: When Margo is talking to Grace in the coffee shop, Grace's bag on the table behind her keeps on altering its position.
Continuity mistake: At the start when Grace joins Will and Karen at the coffee shop table, she begins to make her coffee. In one shot from behind we see her pick up a wooden stirrer. In the next shot her hand is empty and it has vanished. In the next shot the stirrer reappears in her coffee mug. (00:00:40)
Answer: The director, James Burrows.