After Spence takes the hot dog from Doug and Deacon, it cuts to a different angle and Spence is already chewing without having had time to take a bite. In later shots, the hot dog is intact even though Spence took at least two bites of it.
When Doug and Carrie argue with Arthur in the kitchen about him having lost weight, Doug puts one hand on a water bottle and the other on the back of a chair. In the next shot, both his hands are on the water bottle.
In the video store Arthur wants to rent Destination: Istanbul, which he claims is described by Leonard Maltin as Raymond Burr's finest role. There is no such movie.