In the previous episode "The Butler Did It," the couch is damaged and the kids replace it with a new one. In this episode, the couch is back to the one they've used throughout the rest of the season.
When Carlton comes in the kitchen with his book "How to Beat the Odds" and says he has read it cover to cover, you can clearly see when the camera is over his shoulder that the pages of the book are blank except for some lines drawn with a yellow highlighter.