There's Something About Heidi - S3-E2
Revealing mistake: When we are shown Nicki's dream about Mike where they are supposedly both naked, you can see a skin-color band covering her breasts briefly in the close-up of her fumbling the football. (00:07:50)
The Kidney's All Right - S3-E9
Revealing mistake: When Paul has a flashback to when he was bullied by Butch, it is quite evident that the school is the exact same set as City Hall. (00:09:00)
Not in the Line of Fire - S3-E15
Revealing mistake: When James points out to Carter that Rags is eating his sleeping pills, it's painfully obvious that they are actually dog biscuits. (00:06:15)
Not in the Line of Fire - S3-E15
Revealing mistake: Two thirds of the way into the show, Mike and the mayor are talking in his office. If you look at the Mets hat behind Mike, the NY emblem is upside down.
Not in the Line of Fire - S3-E15
Revealing mistake: 1/3 through the show, Stuart is talking to Nicki's boyfriend in the cafeteria, and the candy machine has "N&Ns" in it instead of "M&Ms" for both plain and peanut. The letters have been partially covered up.
Revealing mistake: When the doors to the barn magically fly open to reveal that James has returned, you can see it being opened by someone through a crack in the wall.
Revealing mistake: Whenever the judge's hands are shown, his extra fingers are always unquestionably rigid and still, even while writing. This shows that they are prosthetic (although meant to have been there by birth, which he explains).