Continuity: The set for the Heffernans' living room includes windows on both sides of the front door (the front door is centered between windows), but the view from outside of the front of their house shows the front door next to the right corner of the house with no window in between on that side (all of the windows are to the left of the door).
Continuity: When the outside view of the Heffernans' house is shown, there is no porch. Yet there are multiple episodes were they are on their front porch.
Errors in geography: In a few episodes there is a reference to the characters going to "Dairy Queen". There are no "Dairy Queens" in Queens, or in all of NYC for that matter.
Continuity: The exterior shots of the Heffernans' house from the street shows a screen door on the front door, but when people go in and out of the house on the set, there isn't a screen door.
Continuity: In the episode where Doug brings home a snow cone machine from work, he is in the kitchen with a full snow cone, walks through the door to the living room, and it is almost gone.
Continuity: Exterior shots of the garage show four windows for each door, the interior shots show three windows.
Continuity: In the episode where Carrie boycotts Doug's favourite restaurant, Arthur receives a Video box set on the civil war. The size colour and style of the box set alternates between shots.
Miscellaneous: In one episode Doug and Carrie's wedding is shown. Here you obviously see Carrie's wedding dress. In a later episode where Carrie has become concerned with her weight, she is shown trying to fit back into her wedding dress. They are two completely different dresses.