Continuity mistake: In 1-2: "Post Nasal Dick", Harry has a dream about Martha Stewart. But in this episode they panic because they dream and have nightmares and don't know what they are. Shouldn't Harry have panicked when he dreamed about Martha Stewart?
Continuity mistake: When Jennifer comes into work the next day after her dinner date with Dick, her face is covered in hives from an allergic reaction. Later when Dick interrupts her choral group, the hives on her face have disappeared. She and Dick are wearing the same clothes in both scenes, so she couldn't have overcome such a reaction in such a short amount of time.
Continuity mistake: Dick's plot in this episode is that he learns about the concept of tipping. However, the season 3 episode "Eleven Angry Men and One Dick" showed that Dick was already familiar with the concept of tipping when he tipped a bailiff during a jury selection process.
Add timeSerious B
Continuity mistake: In the scene where Harry and Tommy are sitting in the living room, Sally comes by with a drink for Tommy and the shot changes when she is behind Harry and walking towards Tommy. But in that next shot, Tommy is already holding the drink.
Continuity mistake: When Ms. Dubcek is showing the Solomons the attic apartment in the pilot episode, they enter (and she later exits) through what is Dick's bedroom in all subsequent episodes. Additionally the staircase at the back of the living room that serves as an entry point is completely missing.
Add timeSerious B
Continuity mistake: Dick hands Nina a box full of dishes and asks for them to be cleaned. She then drops the box on the ground where it lands upright. All of the dishes remain in the box. The next time it's seen a few seconds later, it's suddenly on its side with dishes scattered across the floor. None of the characters touch it and there is no sound indicating that it magically tipped over by itself.