Continuity mistake: At the start Doug puts a drink down after taking the top off. Camera cuts and the lid is back on. (00:03:30)
Continuity mistake: When Doug first enters the gym, you can see a price tag hanging off of the front of his weight belt. In the shots following this, the price tag is gone. (00:11:10)
Continuity mistake: The Saskeys are Doug's neighbors in this episode despite them having moved away back in the season 2 episode "Soft Touch" (00:02:30)
Continuity mistake: When we first see Doug at the gym, the sweat stains on his shirt keep changing size. (00:11:30)
Continuity mistake: When Stephanie arrives and Doug says about killing his parents, Stephanie has her hands apart, but when the camera angle changes to a different view, her hands are clasped together. (00:14:40)
Continuity mistake: After throwing the dummy out the door, Doug kicks his bag out the door too, only for it to reappear a few minutes later. (00:18:20)
Continuity mistake: Doug throws the dummy out the front door and in doing so, knocks a green Jets jacket to the floor. In the next shot the jacket is back on the stand. (00:18:40)
Continuity mistake: At the beginning during dinner, Carrie hands Doug the salad bowl, then puts the spoon into the bowl and hands it to him again in the next shot. (00:02:25)
Strike Out - S3-E7
Continuity mistake: When Arthur sits down for his meal, there is a bottle on the table. The lid is either on or off depending on the shot. (00:03:30)
Continuity mistake: When Carrie asks Arthur how a legless dummy will protect her on the subway, her arms are either on the table or off, depending on the shot. (00:10:30)
Strike Out - S3-E7
Continuity mistake: After Doug says "Let's hit the streets", Doug, Arthur, Deacon and Kirby go on a mini crime-spree. During this montage each characters outfit completely changes several times. They are also dressed very lightly for late October/early November in New York. (00:13:00 - 00:14:00)
Strike One - S3-E5
Continuity mistake: When Doug has a look at the bumper sticker Spence has, there is one fold in it, but when it cuts there is now three. (00:14:40)
Continuity mistake: When Doug says that there is nothing going on at work, his hands are flat on the table, camera cuts and he's got one up in the air. (00:06:50)
Inner Tube - S3-E17
Continuity mistake: When Arthur brings the tray to Doug in bed, the position of the duvet/sheet is constantly changing. (00:06:20)
Strike Out - S3-E7
Continuity mistake: When Carrie and Kelly are setting the table, Kelly is handing plates to Carrie. She hands Carrie a plate and has one left in her hands. The camera cuts, and she now has two plates in her hand. (00:06:20)
Strike Too - S3-E6
Continuity mistake: At the end, when Carrie talks about going upstairs, she has her hand on Doug's arm on the back of the sofa. When the shot changes, it's now lying in front of her. (00:20:20)
Strike Too - S3-E6
Continuity mistake: The writing on the blackboard changes between shots when Doug writes his name. Note the R in Mr. (00:15:10)
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.