Continuity mistake: When the four are eating dinner and talking, Will says "Well I don't wanna sleep with you either," and in this closeup Karen picks up her glass of wine. In the next shot the wine glass is back on the table and she's now holding her fork.
Continuity mistake: When we see Jack dancing at the open auditions, there is a grey sports bag behind him which alternates from propped up against the small black chair to sitting in front of the chair on the floor, many times during the scene.
Continuity mistake: In the opening scene with Will, Grace, Jack and Karen, as they open the wine and talk about what they would like to accomplish in life, the newspaper disappears from the table during the scene, then reappears in a later shot.
Continuity mistake: When Karen is talking to the security camera in the cell, before receiving the phone call from Stanley, the pieces of salami strewn all over the bed change and some pieces disappear, most noticeably one piece on the pillow.
Continuity mistake: When Grace is setting up her design class, she writes "Professor" on the board, and curls the end of the R into a spiral. But in the shot when she says "T.A. - Teachers Assistant" the spiralled end on the R has gone. In the next shot it's back again.