When Arthur looks at Doug Deacon and Danny leave through the front door, they close it. Later the front door can be seen still open.
When Carrie complains about Doug always thinking of only himself in the bedroom, she turns her head away. The camera then focuses on Doug and Carrie can be seen on the side, facing him.
When Spence starts making a sandwich, he has the loaf of bread in his hands and then in a blink he has the mustard and then in another blink he has nothing in his hands.
When Carrie grabs Doug and pushes him into the wall to kiss him, the wall moves.