Continuity mistake: Following the argument between Will and Grace when she returns from City Hall, Karen tells Grace she "thinks it's time for a couple of blue bibbies." Watch closely as she removes the lid from the pill bottle, takes out some pills, and puts the lid back on. The scene shoots to Grace and we hear Karen shaking the closed bottle. When the scene shoots back to Karen we see that the pill bottle is open again and Karen closes it yet again.
The Truth About Will & Dogs - S1-E10
Visible crew/equipment: In most of Season One at least (choosing a specific moment here), Will and Grace have a large ornamental silver ball in their living room, which always reflects the studio lights and the fact that there is no fourth wall to the apartment. (00:27:35)
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 and Grace sit on the rocks in the meditation room, at the end of the episode, the position of Grace's coat changes between each shot. (01:22:00)
Where There's a Will There's No Way - S1-E7
Revealing mistake: When Grace slams into the side of the elevator buttons, they all light up except 4 (which is supposed to happen), but 5 lights up after she moves away from the panel. (01:22:30)
Will on Ice - S1-E11
Continuity mistake: When Will and Grace play the "love her, hate him" game, they open a magazine up. In the next shot you can tell it's on a different page, because the layouts have changed. (00:05:45)
Boo! Humbug - S1-E5
Continuity mistake: When Will grabs the silly string from the table, he pulls off the yellow lid and drops it to the floor. In the next shot the lid is on the coffee table. It alternates from on the table/floor for a few following shots as well. (00:59:25)
Continuity mistake: When Will introduces Grace to April, the pencils in Grace's hair changes between shots.
Between a Rock and Harlan's Place - S1-E4
Continuity mistake: When Will and Grace are eating dinner, Will has his knife and fork in his hands, but in the very next closeup he his wine glass in his hand. (01:05:00)
Visible crew/equipment: When Grace asks Will for his advice on where her mirror in her new apartment should go, she goes running to the wall and when she does, the camera pans over and you can see that the wall stops, revealing it to be a set.
Visible crew/equipment: In the scene where Grace shows Will the new apartment for the first time, you can see the boom microphone pop into the top of the frame several times.
The Big Vent - S1-E9
Continuity mistake: After giving Will and Grace his scripts to read, Jack places his drinks bottle on the table and walks over to the door. When he reaches the door he suddenly has the drinks bottle in his hand, although he left it on the table across the room. (00:47:00)
Continuity mistake: When Will is sorting his CD's, Grace enters the flat and puts her bag on the sofa with the back facing out and it is all black. When Will gives Grace a glass of wine, the front of the bag is facing out, with the flower design. (00:05:10)
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)
