Continuity mistake: Arthur and Doug are sitting with beers in the basement. Arthur doesn't open his beer, but the sound of a bottle opening can be heard and suddenly his beer has foam all the way up to the top of the bottle. Arthur stands up and the bottle is still unopened. It cuts to Doug, then back to Arthur with no beer at all. Again it cuts to Doug, then back to Arthur, and he is holding the unopened beer again. (00:18:30)
Continuity mistake: While Doug is sitting on the corner armchair reading, Carrie's on the sofa holding her coffee mug and magazine, but when she tells Doug to join her on the sofa her coffee mug vanishes from her hand, and then it reappears. (00:01:00)
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.