Continuity mistake: After Spence suffers from his allergic reaction to peanuts he's seen lying on the couch. Doug then says something to the effect of having to scrape Spence's lunch off the fence, indicating that he threw up. But the allergic reaction took place before they got to the lunch.
Continuity mistake: Doug finishes playing the tennis game on the TV with Arthur and goes into the kitchen to get the Cheese Doodles. While talking to Carrie, he puts the Cheese Doodle package on the table with a can of cola behind it. He then goes to get a glass from the cupboard and in the next shot you see the cola is in front of the Cheese Doodles.
Revealing mistake: In the final scene of the episode, Arthur is searching for used bottles of nasal spray. He empties the contents of the trash can on the kitchen floor and finds one after sifting through the trash. However, the bottle had already been positioned on the floor next to the trash can before he picked up the trash can so it would be easy to find when the trash was emptied on the floor.