Deconstructing Carrie - S7-E15
Continuity mistake: In the kitchen when Arthur says he was a terrible father and gets up, Holly looks over at him with her hand on the edge of the table. She says, "Oh no", but then she's smiling. When the shot changes angle, her arms are crossed. Then Holly says, "Better than my dad, who was too busy chasing the almighty bottle of glue", her hand is instantly on the box of photos again. (00:11:35 - 00:12:05)
Deconstructing Carrie - S7-E15
Continuity mistake: Doug is sitting on the couch making club music sounds and moving his hands when Carrie reaches out and touches his face to make him stop; then his left hand is instantly on the arm rest. (00:13:10)
Deconstructing Carrie - S7-E15
Continuity mistake: While Carrie was being harassed by the construction workers, Doug was watching by looking out the door to the right. In the next shot, you see Carrie through the window, coming in from the 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.