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)
Move Doubt - S8-E8
Visible crew/equipment: Season 8, episode 8 "Move Doubt": When Carrie and Doug leave Kelly and Deacon's apartment, you can see the shadow of a boom mic on the wall to their left.
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.