Continuity mistake: As Leo speaks with Diane (he's on the sofa; she's in a chair) she refills her wine glass until it is nearly full. In the next shot Diane takes the last sip of wine from her glass, and the following shot shows her glass nearly full again. (00:08:45)
Boo! Humbug - S1-E5
Continuity mistake: When Jack and Karen are downtown on the streets, Karen wears a red shawl, and in one shot she pulls it up so it is over her shoulders, but in the next shot it is down by her elbows. (00:53:25)
Heart Like a Wheelchair - S6-E6
Continuity mistake: When Karen is getting a boost on Lyle's shoulders to go through the window above the apartment door, she puts her right hand on his head, yet in the next shot her left hand is the one on his head. (00:08:05)
Revealing mistake: Will is reading a book in the total nude on the sofa, and then Leo walks in on him. When Will gets up from the sofa to run into the bathroom, you can blatantly see pants around his waist as he gets up from the sofa and runs to the bathroom.
Continuity mistake: The position of the high heels in the barrel, in the church bazaar differ greatly between shots as Karen enters the room, up to when she walks over to find her slingbacks. No-one else touched the shoes in between. They also change position as Karen kindly gives Sally some extra money. (00:57:25)
Where There's a Will There's No Way - S1-E7
Visible crew/equipment: When Karen enters the office with clothes and bags, Grace says "Oh Karen, you didn't have to buy me clothes," and above her is the whole boom dipping into view. (01:05:40)
Continuity mistake: The amount of frothy foam on top of the protein shake differs through consecutive shots, as Grace is about to drink it, and after she has taken a sip and as Will and she talk in the kitchen area. (00:20:55)
Three's a Crowd, Six is a Freak Show - S3-E10
Revealing mistake: Grace's boyfriend has six toes but in closeup shots, when he takes off both socks you can clearly see only five toes on each foot, when they are specifically trying to hide one foot.
...And the Horse He Rode in On - S5-E1
Continuity mistake: When Karen walks into her bedroom, she pulls her bed sheet up to discover Jack underneath. The bed sheet now hangs down over the end of the bed. between following shots the position of the bed sheet keeps changing.
To Serve and Disinfect - S2-E6
Continuity mistake: When Brian is asking Jack where his steak is, because Jack is waiting and doing a job as a pepperboy in the restaurant, between shots the large wooden pepper grinder which Jack is carrying, vanishes. (00:59:25)
Continuity mistake: When Will is talking to Jack and is folding tea towels, he folds the same tea towel twice between shots. (00:01:30)
To Serve and Disinfect - S2-E6
Continuity mistake: After Grace plays Karen's adult video, Karen drops her compact, and powder spills all out of it onto the table. In following shots the powder on the desk changes position and vanishes. In addition the compact case also moves too, and when Karen dropped it onto the table it snapped shut but in a following shot it is open again. (00:50:00)
Guess Who's Not Coming to Dinner - S2-E1
Revealing mistake: When Will is supposedly naked, reading his book, you can see he is wearing underwear when he slams the book down as Grace leaves. (00:08:30)
Boo! Humbug - S1-E5
Continuity mistake: When Will and Grace are taking the kids around the flats trick or treating, as Will and Grace enter the lift, the kids stand in the hall and their pumpkin bags have faces, but in the next shot they are plain orange. (00:56:05)
Big Brother is Coming (1) - S1-E14
Continuity mistake: When Will is throwing ties from the closet, we see that they all land on the floor. The angle changes, and one has now appeared on the bed. (00:08:50)
Continuity mistake: When Grace is putting on the waterworks in front of the landlord, to get a lower cut on the apartment, the bowl of tassels on the table is repeatedly full/half full, and tassels jump in and out of the bowl. (00:16:00)
Lows in the Mid-Eighties (2) - S3-E9
Factual error: When Will and Grace bump into each other in the supermarket in 1986, more recent items and brand names can been seen in the fridges and on the shelves during the scene.
Continuity mistake: After Will and Grace find Karen asleep on the top of the sofa, Karen sits down on the sofa, and puts her beer bottle on the couch next to her. When Grace comes over with her holiday photos, the bottle has gone.
Alley Cats - S1-E21
Continuity mistake: When Rob & Ellen are confronting Grace about how competitive she is, there are several shots of them from the same angle. In some shots there is a red bag visible in the bottom left corner, in others it disappears.
