Queasy Rider - S2-E1
Audio problem: When Doug enters the kitchen wearing his leather jacket and tells Carrie he just got in from riding the bike, you can see the bike parked just outside the kitchen window in the backyard. If that was true it would have been heard from inside the kitchen, as motorcycles are quite loud. (00:11:35 - 00:12:15)
Queasy Rider - S2-E1
Revealing mistake: We see Doug crash into the fridge 3 times, thus implying that it's 3 times he's crashed. However it is the same clip used for all 3 crashes. (00:13:40)
Queasy Rider - S2-E1
Visible crew/equipment: When Doug and Carrie are arguing over the bike a white tape marker can be seen on the floor. (00:09:20)
Queasy Rider - S2-E1
Continuity mistake: When Doug is checking Arthur's CV at the start, the items on the counter keep moving - noticeably the mayo and lid. (00:00:25)
Queasy Rider - S2-E1
Continuity mistake: When Spence is talking to Carrie at the restaurant at the start, Spence has his hands out in front of him. Camera cuts to another angle and now he has his drink in his hand. (00:01:45)
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.