Continuity mistake: When Doug is being a polar bear, the bag Carrie was looking in disappears. (00:08:00)
Continuity mistake: When Doug asks Carrie to take a photo of him on the bed, there is nothing on the bed. After she says "stop", 2 items have appeared on the bed that were not in the previous shot. (00:08:45)
Continuity mistake: When Tim asks Doug if he wants to tee off back at the start of the hole rather than halfway down the fairway, he is pointing with his golf club. Camera cuts and he isn't. (00:15:35)
Continuity mistake: When the Marshall is chasing after Doug the distance between the two changes drastically. (00:16:00)
Continuity mistake: When Doug and Carrie are told that mold isn't covered by their insurance, Doug has his fist clenched by his mouth. Camera cuts and now it's open palmed and on the side of his head. (00:01:00)
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)
Visible crew/equipment: When Carrie hugs Doug and wishes him good luck, you can see the battery pack for her mic in her jeans. Clear as day. (00:17:35)
Visible crew/equipment: During the drag race at the end, several times on the van you can see camera shadows. (00:19:10)
Character mistake: The woman in the store claims that the umlaut on the shoe size indicates a half size in Europe. This is wrong because the European shoe size system (used in Germany among others) is completely different from the US system. Carrie's 6 1/2 shoes would be a size 39 according to the European system.
Continuity mistake: When Doug and Carrie are arguing over Arthur having a house, the head on Doug's beer keeps changing size. (00:02:00)
Revealing mistake: Both times when you see an overview of the bridge, it's the same clip being used. (00:07:10)
Visible crew/equipment: The second time Doug pulls up at the toll booth, stage lights and equipment are reflected in the car's paintwork. (00:07:20)
Dog Shelter - S5-E23
Visible crew/equipment: When Doug finds out that Rocky is in fact Rocky 4, a boom mic is reflected in the window. (00:10:20)
Dog Shelter - S5-E23
Factual error: Rocky the dog, who turns out to be Rocky IV, is a mixed breed. It would have been impossible for Doug's parents to find three more adult dogs who looked near identical.
Taste Buds - S5-E24
Other mistake: When Doug sits down to eat and Arthur touches his food, Doug says, "That's what my sandwich was missing, a finger with a loose bandaid on it," and pushes Arthur's hand away. When he does this you can see Arthur isn't wearing any bandaids on his hands. (00:00:05 - 00:01:00)
Taste Buds - S5-E24
Continuity mistake: Just after Carrie tells Doug that she knows what he has been doing, she storms out of the kitchen. Doug has his hand on a water bottle on the table, then picks it up as he rushes after Carrie. In the next shot of Doug walking into the living room, the water bottle is gone.
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.