The window in Carrie's office shows the neighbor's house but that window should be facing the backyard and garage not side of house.
When Carrie makes up the futon for Arthur, she puts the flat sheet on the bottom and the fitted sheet on top.
After Arthur turns the thermostat up to 90 degrees, Doug and Carrie both wake up in the morning and say that they're drenched with sweat. Although Doug's clothes have sweat marks, Carrie's clothes and the bedsheets are both dry.
The opening scene revolves around Doug and Carrie trying to scrape ice off of the car windshield. They never bother to start the car to warm it up and defrost the windshield.