Maxwell's age is inconsistent - for several years it remains at 42 yet in the 3rd season goes to 41.
Many times it is said that Fran's mother Sylvia is desperate to be a grandmother, and that Fran hasn't made her one. But Fran has a sister who has children, so Sylvia is already a grandmother.
The bedroom arrangement constantly changes. You can see them use the bedroom near Maxwell's room for all three kids through out the series. You can even see Brighton going into Maxwell's room when being told to go into his own.
The establishing shot of the Sheffield townhouse shows two upstairs windows- one above the entrance door and the other to the right. A window mounted air conditioner appears and disappears as different shots are used.
When people are leaving through the inner front door, they often turn right (exiting the stage) rather than going through the outer front doors. While not noticeable from side views of people leaving, his flaw can be seen from shots behind the characters as they leave.
Nearly every episode, every set-up, every storyline, every character and even the props and decor are lifted from the popular 80s sitcom, "Who's the Boss?". Drescher guest starred in 2 episodes, one of which was supposed to be a spin-off and her big breakout role. Instead, 10 years later, she produced for herself this uncredited "spin-off".
The layout of the Sheffield house constantly changes, particularly in the area of the kitchen. Sometimes the door to the right opens to a hallway, sometimes the dining room, and sometimes into a butler's pantry. The upstairs is equally confusing with the location of the bathrooms and bedrooms constantly changing locations.
A running joke during the series is that Sheffield passed on the musical "Cats," which was a huge success. However, since the show was written by Andrew Lloyd Webber- Sheffield's supposed nemesis, it would never have been offered to him in the first place.
During the opening credits, Fran is kicked out of the bridal shop and a 'help wanted' sign is placed in the window. In the pilot however, Danny tells Fran that his new girlfriend needed a job so he was firing her. There was no need for a 'help wanted' sign.