Continuity mistake: When Carrie is talking to Tina about playing 3 holes, her hands are outstretched. Camera cuts and her gloved hand is now on her hip. (00:16:40)
Continuity mistake: Arthur gives Holly a book at the start and she has it in her right hand. Camera cuts and now it is in her left hand. (00:03:20)
No Orleans - S4-E16
Continuity mistake: When Spence is seen eating a snow cone for the first time, the level of it changes between shots. (00:06:10)
Continuity mistake: Arthur grabs a spoon to have some of the brie, camera cuts and he grabs the spoon again. You hear him take the spoon twice as well as it clangs on something. (00:04:15)
Revealing mistake: When Carrie is talking about going to the fertility clinic, you can see the fridge behind Doug through the door. If you look closely just before the camera changes a boom shadow moves across the fridge. (00:01:35)
Continuity mistake: Doug closes his magazine at the start. His thumb is in the pages. Camera cuts and now his thumb is on the cover. (00:01:00)
Audio problem: When the nurse compliments Doug on his costume, she taps him on the arm twice. However the sound is out of sync. (00:08:00)
No Retreat - S4-E5
Continuity mistake: When horseback riding, the track behind them is constantly changing. For example, when Doug hits the tree, the tree then vanishes. (00:17:40)
No Retreat - S4-E5
Continuity mistake: When Doug tells Carrie at the start he is telling his jet ski story, the tongs he's holding swap hands instantly. (00:00:45)
Continuity mistake: When Arthur and Spence are talking in the kitchen, a fork keeps appearing and disappearing from Spencer's plate. (00:05:40)
Continuity mistake: When Doug and Carrie are talking about the fact the workmen have actually turned up, the cup on the table keeps rotating with no-one touching it. (00:12:15)
Continuity mistake: When the Marshall is chasing after Doug the distance between the two changes drastically. (00:16:00)
Continuity mistake: When Doug is being a polar bear, the bag Carrie was looking in disappears. (00:08:00)
Continuity mistake: When Carrie is on about having never spent that much on a vacation, she has a leaflet in her hand that is open. Camera cuts and now it is partially closed. (00:03:10)
Continuity mistake: When Tim and Doug are talking about the pool overlooking the property, the way Tim holds the ball changes between camera cuts. (00:15:00)
Visible crew/equipment: When Doug gets the beach ball, all the stage lights are reflected in it. (00:14:00)
Continuity mistake: When the guys are having brunch, Kelly has got her mug in her hand. Camera cuts and her grip has changed on the mug completely. (00:06:40)
Continuity mistake: The Heffernans have neighbors on both sides of the house as seen in previous episodes. However there is no house to the left of theirs when we see Lou at the very start. (00:00:40)
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.