Continuity mistake: During the first shuffleboard scene, the characters are brightly lit and cast by long dark shadows (indicating early morning or late afternoon), but when you see shots of the shuffle pucks flying into the bleachers, the bleachers' and extras' shadows are cast straight down (indicating noon hour).
Continuity mistake: When Arthur asks Doug for a game of ping pong, a ball suddenly appears under his bat and then disappears and Doug throws him the ball to have the first serve.
Other mistake: Carrie says that Deacon doesn't drink or smoke. Many episodes have shown Deacon drinking a beer or a margarita.
Visible crew/equipment: When the camera cuts into the wide shot of Carrie leaving the store, the camera rig to the left of the screen is almost entirely visible. You can see it follow Carrie around for a good 10 seconds. (00:10:35)
Cheap Saks - S6-E15
Visible crew/equipment: While Doug reaches for the phone when Trish is calling you can see where the kitchen wall is ending on the set. (00:11:53)
Factual error: Doug goes to the doctor for a check up after losing some weight. They live in New York, but the address on the outdoor sign is actually in California. (23101 Sherman Pl).
Character mistake: Doug claims to be a Pisces, however during this episode when entering his birthday into the alarm system to disarm it he calls out 2-9-69 which shows he would be an Aquarius.
Continuity mistake: While Arthur tries to convince Spence about the card, when Spence bites into the fake cookie he's holding it in his left hand and holding the plate in his right hand, but in the next shot facing Arthur the items have switched hands. (00:16:30)
Continuity mistake: When Arthur asks Doug for a game of ping pong, the paddle is lying flat on the table. In the next shot there is a ball under the paddle which Arthur picks up (The ball is still on the table). In the next shot the paddle is back on the table and the ball is missing. (00:03:15)
Revealing mistake: When Doug snaps his bat it's very clear it is pre-broken. (Possibly from a previous take or to make it easier for Kevin James.) (00:07:55)
Visible crew/equipment: When Carrie walks in and sees Hollie for the first time in the episode, a boom mic can be seen following Carrie across the kitchen. (00:07:00)
Continuity mistake: The second time we see Doug's disk, it is spinning. In one shot it is spinning in shadow, but in the second shot it is in the sunlight. (00:08:00)
Visible crew/equipment: When we see Arthur playing Shuttleboard for the first time, his mic pack is visible. (00:08:00)
Answer: Sara hasn't been mentioned in later episodes, and it suggested in later episodes that she never existed, and that Carrie is an only child. Kevin James stated that the producers couldn't think of an good plots to use with Sara, so they left her out.