Continuity mistake: When Doug and Carrie are in the living room talking about Doug not going out with Kelly again, he has the phone in his hand, gets upset and throws the phone down. Then Carrie is going to call Kelly for Doug, and when she goes to pick up the phone, it's placed perfectly back on the hook when it should be hanging near the floor from the way Doug threw it.
Continuity mistake: In the episode where Priority Plus is mentioned, after the Priority Plus driver has got Doug Out of the drive through, he gives Doug a lift in his truck. In some shots there is a window on the side of the street. In the window there is no Priority Plus truck visible.
Move Doubt - S8-E8
Continuity mistake: Near the end of the episode when Doug and Carrie are at Deacon and Kelly's apartment, you can see a picture on the wall in the hallway behind them. Then when Doug and Carrie leave, the wall is much further back and there's a window and plant instead of the picture on the wall. (00:19:40 - 00:20:45)
Continuity mistake: Deacon says "How do we know cutie-pie isn't cutie-guy?" then crosses his arms. In the next shot his arms are immediately uncrossed and on his hips when Doug replies. (00:06:00)
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.