Continuity: When Jack holds his glass of water, he changes from holding the stem of the glass, to the actual bulbous part of the glass between shots.

Plot hole: In the episode "Lows in The Mid-Eighties" during the flashback scenes, it is shown to us that Will comes out of the closet during his freshmen year of college during Thanksgiving Break, when they spend the weekend at Grace's Parents house. However in the episode "Willian, tell" Grace claims that Will came out to her at senior year of college during Christmas Break. Quite a difference for such a memorable time.

Continuity: When Karen is talking with Norman about donating funds for his advert, and then when Jack enters, between shots during the scene Karen's pearl necklace keeps jumping in and out of her black shirt.

Continuity: When Grace is reading through her diaries, through all following shots in the scene the position / location of the yellow, furry diary on the floor keeps changing.

Plot hole: The apartment block where Will lives supposedly has the same layout for each floor of the building. Yet in "Yours, Mine or Ours" the room 12D is seen as located right in front of the elevator, the same location as Will's apartment door - however Will's apartment is always seen as 9C.

Continuity: In the opening scenes, Grace has red nail polish on. Later in the same scene, it has vanished as she shakes Mrs. McFarland's hand.

Revealing: 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.

Revealing: At the party it is obvious none of the red plastic cups have drink in them.

Continuity: When Grace finally decides to move into Will's apartment near the end, we see Will eating a tub of ice cream. Between shots the ice cream tub lid jumps from being on the table behind Will, to suddenly sitting right in front of him.

Continuity: When Karen is sorting out her clothes at her work desk, the black sweater hanging over the desk lamp disappears then reappears.

Continuity: When Grace is telling Will about his dad's affair, she mentions that he grabbed the other woman's ass when she brought him a packet of Goobers during the interval. The thing is, she sees them for the first time during the interval, and we see the conversation that follows. The mistress brings him wine, not Goobers, and he doesn't grab her ass.

Plot hole: Ellen and Rob wear wedding rings, yet their wedding is not announced until "An Affair to Forget" in the second season.

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: When Ellen says to Grace "Okay, what do you mean Will and You have never done it?" the red plastic cup she holds swaps hand three times between shots.

Continuity: When Grace enters Will's office, while he is spinning around on his new office chair, she goes and puts her black purse down on the desk. In the next shot it is positioned differently.

Continuity: After Jack and Karen have locked Will and Grace in the bouncy castle, Grace throws her black purse down into the corner, then her and Will start talking. During their conversation the position of the purse keeps changing.

Continuity: After Kevin throws the contract paper down onto Will's desk, the items on Will's desk, and the contract itself, change position a few times in the following shots.

Continuity: During the dinner scene at the start, the white napkin at Karen’s placemat vanishes between shots.

Continuity: When Grace is in the batting cages, she gives Will some money to go buy her a corn dog and some nachos. The door to the cage is wide open, but in the very next shot of Will, the door is locked shut.

Continuity: When Will and Grace are talking to the nun about buying the car off of her, the amount of Burberry scarf showing out of Will’s coat is inconsistent with each shot change.