In the basement, when Doug starts yelling at Arthur, Arthur begins to walk away and out of the house. We then see Arthur on the sidewalk outside while Doug continues to yell. Doug then comes running to Arthur and they make up. This is a homage to a scene in the film Rocky (1976), when Rocky starts yelling at Mickey and the same thing occurs.
Notice in this episode the Heffernans refrigerator/freezer is a top freezer bottom refrigerator. In all other episodes their refrigerator/freezer is a side by side.
In the beginning when both Doug and Carrie have their heads in the freezer, when camera angle switches to see their faces, you can see the unseen "fourth wall" of the kitchen.
When Doug is yelling at Arthur in the basement, you can clearly see the front of a camera on the right side of the screen, as they pan out while Arthut leaves.