Train Wreck - S1-E20
Visible crew/equipment: At IPS, while Doug gives his speech about using heavy package stickers, in the shots facing the drivers seated at the table, the end of the IPS set and a crew member are visible at the right side of the screen. (00:08:45)
Revealing mistake: At the start, when Arthur returns the book to Carrie then asks if she'd like to jot down his musings, we can see through the back door's window, and the backyard set's foliage pattern wallpaper is falling off the backdrop. It's visible later as well. (00:02:45)
Revealing mistake: After Doug successfully trades vacation days with Roger, it cuts to Doug's IPS truck stopping in traffic. The next few shots were filmed on the streets at Sony Pictures Studios lot. In the shot of the IPS truck's side-view mirror (as the RV approaches), note the signs on the building read "Keaton Building" and "Sound Department Courtyard." After the flashback, another building sign reads "Durante Building." These buildings are located at the north side of the studio in Culver City, CA. (00:03:20)
Visible crew/equipment: During the flashback, when Carrie walks over to Doug at the side of the house, and he zips himself up, in shots facing Doug, a crew member and production equipment are visible on the right side of the screen. (00:20:10)
Visible crew/equipment: During the flashback, while Doug is waiting on the porch Carrie rushes out then gets into her car to take off, and in the next shot facing the front door, the reflections of the camera operator, wearing a white baseball cap, and the camera are visible on the window. (00:12:35)
Soft Touch - S2-E22
Visible crew/equipment: At the start, in the shots facing Carrie and Doug while they're in the car, we can see a screen atop the roof on the driver's side of the car with its reflection on the windshield (and its shadow on the car's hood). This is gone in the overhead long shots. (00:00:10)
Continuity mistake: When Doug puts down the remote to grab Carrie's Walkman, the position of the remote changes between shots. (00:00:45)
Food Fight - S4-E13
Continuity mistake: When Arthur tells Doug to eat some salad he is either holding the bowl or not depending on the shot. (00:18:40)
Food Fight - S4-E13
Continuity mistake: When Spence and Becky arrive near the end, Doug's coat on the floor changes position with no-one touching it. (00:17:20)
Food Fight - S4-E13
Continuity mistake: When Doug is checking the mail while telling Carrie about checking the food twice a week, the letter at the back of the pile is red. Camera changes and now it's a normal envelope. (00:05:30)
Continuity mistake: Doug gets into a mess with the sellotape wrapping Carrie's Christmas present. However when she walks downstairs it's on the table, absolutely fine. (00:02:20)
Visible crew/equipment: In the church just as the minister tells Doug and Carrie to take a seat, two white tape markers are visible on the red carpet. (00:05:30)
Continuity mistake: When Doug is speaking to Spence and Deacon about Carrie throwing up, Spence takes the cap off his beer which reappears a few shots later. (00:02:45)
Visible crew/equipment: When Doug says he doesn't want to look after Arthur in the bedroom, there are 4 tape markers visible on the floor at the foot of the bed. (00:14:30)
Continuity mistake: When arguing with Arthur about moving upstairs, Carrie has her hand on a chair or the table depending on the shot. (00:05:50)
Continuity mistake: When Arthur is talking to Doug in the hospital, the pillow behind Arthur keeps changing position. (00:11:00)
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.