Plot hole: Ellen and Rob wear wedding rings, yet their wedding is not announced until "An Affair to Forget" in the second season.
Continuity mistake: When Karen is sorting out her clothes at her work desk, the black sweater hanging over the desk lamp disappears then reappears. (00:26:40)
Continuity mistake: 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. (00:42:00)
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.
Visible crew/equipment: When Jack is explaining to Will how to visualize someone else while kissing them, you can briefly see a blue mat in the bottom right corner of the screen. This is where Karen later faints. (00:11:55)
Alley Cats - S1-E21
Plot hole: When they are bowling and Grace is losing, she says she's fine with it and she knows how it feels to be her middle sister, then Will reminds her that she's actually, "The baby of the family looking for Daddy's approval." However, in all later episodes, Grace is portrayed as the middle child with a younger sister, Joyce and an older one called Janice. This mistake is made in a few other places through the show, where Grace either refers to how old she is (youngest, middle child etc) incorrectly.
Continuity mistake: After Karen takes her black top off and throws it down on the table, whilst talking to Jack as they first meet, in following shots the top changes position a few times. (00:37:40)
Visible crew/equipment: When Karen offers her hand to Jack when they first meet, you can see the boom mike at the top of the shot. (00:37:25)
The Unsinkable Mommy Adler - S1-E13
Continuity mistake: 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. (00:37:40)
Continuity mistake: In the poker scene at the beginning of the pilot we witness Will, Jack, Rob, and others playing cards. Shortly after Jack asks for "four cards please" watch the bottom left of the screen as a hand (presumably Will's) deals Jack a single card. In the next shot Will appears to have not dealt Jack any cards yet and when he does he gives Jack five cards, add that to the single card he gave in the previous shot and the Ace Jack kept from his original hand and we get a total of seven cards. Two more than Jack should have had if the hand was dealt correctly.
The Truth About Will & Dogs - S1-E10
Visible crew/equipment: When Grace is trying to persuade Will to come out to the cinema with her, the boom mic is visible at the top of the shot. (00:34:35)
Continuity mistake: When Grace gets out all the videos which hint Will's 'secret', she puts the bag on the table, but in the next shot it's in her hand. Between these same shots a sticker also appears on one of the video cases. (00:29:50)
Boo! Humbug - S1-E5
Continuity mistake: At the end of the episode, "Buzzy Wuzzy" takes her bee mask with her and they leave. But when Will and Grace dive for the jawbreaker, the bee mask is back on the coffee table. (01:01:25)
Continuity mistake: When eating in Will's office, Grace eats salad from a plastic container. Through the scene the salad in the container changes colour, position etc. Also between shots, lettuce appears on Grace's fork. (00:28:05)
