Plot hole: When Theo is complaining that his father is inviting too many people to his graduation, he says "I saw him in the backyard 5 minutes ago hosing down the beach chairs", but this couldn't have been possible because in fact, Cliff was upstairs right before that scene, and then went straight to the living room, so there's no possible way that Cliff could have been in the yard at the time Theo had said he was.
Revealing mistake: When Stanley comes into the kitchen he has three demands, on paper from Deirdre, to which Kenny must agree. After Stanley reads the demands, Kenny signs it. You can plainly see that the paper is blank the moment after he signs it and gives it back to Stanley.
Continuity mistake: At the end of this episode, when Clarie enters the kitchen and closes the doors behind her, they are left a bit open. They remain open while Vanessa and Dabnis also enter the kitchen to say goodbye. When they leave and Clarie asks Cliff something, the doors are now completely closed.