Other mistake: When Doug is saying that Arthur does nothing that Deacon just listed, there is a camera angle of him walking down the aisle with Deacon. In this camera angle only there is a blip to the top right of the screen. This little black mark stays in shot while the camera is moving and is only in this one angle. In other shots of the same angle the black mark is not present. Clearly something was on the camera lens during filming. (00:05:30)
No Retreat - S4-E5
Other mistake: In the opening scene when Doug is cooking hotdogs for his friends, the smoke coming from the BBQ is very fake. (00:00:20)
Other mistake: At the end when Doug takes the bandages off Carrie's face, the bandages come off far too easily as if they weren't really attached in the first place.
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.