Continuity mistake: After letting Campbell out, Grace pulls the white blind down the door, and it stops about halfway down the door, and gets stuck, and is still rolled at the bottom. In the very next shot, the white blind is now unrolled all the way down perfectly. (00:07:00)
Continuity mistake: When Will is cleaning the tray, and in all following shots, from when he leaves the room, to when Karen walks over to Grace, to tell her to go get Campbell, there is a wine bottle which keeps jumping from the edge of the blue sink counter, to the edge of the counter which has the cooking gas-hobs on it. (00:09:55)
Continuity mistake: When Will is standing cleaning a tray, on the counter behind him there is a large circular wooden board, with a white tea-towel sitting on it. After he cleans the tray and walks off, the white tea-towel has moved off the wooden board, and is on the edge of the counter. (00:09:55)
Continuity mistake: When Val is folding her towels in the laundry room, she completely folds up a towel as Will enters the room. Then she is seen re-folding the same beige colored towel. Then, though she had picked up the beige one, she is seen setting a dark towel on the stack. (00:25:45)
Continuity mistake: When Karen is sitting at her desk, she says "get out, already," and she has one bottle of nail varnish in her hand, and there are bottles on the desk in front of her. In the next shot she holds about four bottles in her hand, and now the bottles on the desk in front of her are differently positioned. (00:29:25)
Continuity mistake: When Karen is lying on the table, her jacket is unbuttoned. And when Jack pushes her off the table and she gets back up, it's still unbuttoned. But as the shot cuts to her heading quickly over to the door, her jacket is now buttoned, but there was no time for her to do it.
Continuity mistake: Grace unpacks her Scrabble board game from her bag, and puts it on the table, and puts the bag on the floor. Then her friends tell her she is too competitive, so she goes to her bedroom. As she goes, you can see that the board game on the table has now been replaced by the big red bag. (01:10:05 - 01:11:55)
Plot hole: In the bowling alley scene, Ellen states that Grace would need to knock down 27 pins in order to tie. Will and Grace then have a conversation, and Grace gets a strike with her next ball. They then start gloating that they have beaten Rob and Ellen, but the scores don't add up, and they couldn't go into the lead on that round.