Plot hole: In the episode "That's my Boy" when they bring Richie home from the hospital, Rob and Laura are living in the new house they have. However, in the episode "Where did I come from" when Laura went in to labor, they lived in a different house. They couldn't have moved while Laura was in the hospital.
Continuity mistake: The buildings seen from the window of Rob's office change in different episodes.
Other mistake: Mainly in "Who Stole My Watch?" and 2 other episodes the the Petries and the Helpers talk about the Helpers dog, but there is no dog, the dog doesn't have a name they keep saying "our dog" or "their dog", and there's no dog house, water bowl or food bowls for a dog at their house in any episode.
Continuity mistake: The number of glass "pea pod" shaped sphere balls change through out the series. In "Don't Trip Over That Mountain" there were only 3 spheres. In several episodes there were 4 spheres and in others there were 5 of them.
Other mistake: The crew members behind the camera are talking to each other and taking pictures when Rob and Laura kiss, throughout the series in a few episodes you can hear the camera shutter sound.
Other mistake: Any time Rob has to go to a doctor or to Jerry to get his teeth worked on, if you look at the window behind him and whoever is working on him. It's the same buildings every time. Even though he goes to different doctors. Also, that window and the curtains are also the same exact windows and curtains in Robs office.
Continuity mistake: Every 4 episodes the table in the living room changes completely, one episode it's a huge oval table, in another it's a medium-sized round table, in another episode it turns into a very small round table, some times it's even a large egg shape.
Factual error: Rob mentions several times "I broke my cheek" if he actually broke his cheek we could see a spot there, either a divot in his face where the accident happened and was not fixed, or we would see a indent line from where they put stitches on his face. We see neither of these.
Deliberate mistake: While Rob is on his honeymoon, as well as 3 day pass, things like that, Rob still wears his army outfit. Yet in real life us real humans wouldn't be wearing the same clothes every time we were out. We would go home and change.
Factual error: Alan Brady and Mell's offices are a few floors up. Yet Rob, Buddy and Sally's office window shows that they are way higher up than Alan and Mell's office - you do not see the roof tops of buildings anywhere from Alans and Mell's offices.