Continuity mistake: After Jack brings the puppy over to the girls, the box he brought the puppy in was placed on the table behind their couch. At one point, it is knocked over, and you can see it falling down to the floor (past Janet). In the next shot, it's back on the table, and none of the characters were in a position to pick it up to place it back there.
Continuity mistake: Larry gives Cindy and Janet gifts to thank them for letting him live with them, so Janet gives him a kiss. However, three seasons later in the episode "Friends and Lovers," Janet kisses Larry at her wedding to which Larry says "Janet, that's the first time you've ever kissed me."
Continuity mistake: This is such an obvious mistake. In the scene where Jack, Janet and Terri are on the air for the cooking show, Janet holds up the silver bowl but there is no parsley in it. Then in the next shot the bowl is full of parsley. How is it possible that it got filled up in a matter of two seconds.
Continuity mistake: While Jack is talking to the police officer about the missing rent money, they are standing in front of the TV set and the front door is open. When it cuts back to Jack and the officer, over Jack's shoulder the front door is closed, but when the officer turns to leave the door is open again.
Continuity mistake: In the scene where Jack's uncle first walks in the house to greet Jack, his uncle says, "I thought I'd drop in and visit my favorite nephew." Jack then responds with, "Well I'm your only nephew." But in Season 4, Episode 21 ("Lee Ain't Heavy, He's My Brother"), we meet Jack's brother, Lee Tripper.