Continuity mistake: Alan is sitting at the kitchen table talking to his son Jake about a math test on which Jake got a bad grade. At the beginning of the scene Alan holds the open test in his left hand. When the camera switches back to him a second later the test is now in his right hand. Finally at the end of the scene the test is back in his left hand but is now folded.
Continuity mistake: When Alan and Charlie are watching Judith take off her clothes on the monitor screen, Alan takes the newspaper he has in his right hand and puts it in his left hand to turn the monitor off. The next shot shows Charlie walking into the kitchen and Alan looks at him but now the paper is back in his right hand.
Continuity mistake: During this whole episode, Jake calls his mother's boyfriend Greg. But in the 4th season when Judith is marrying the guy, he is called Herb. We know that it is not two different people because they both have the last name Melneck, and they are both Jake's pediatrician.