Continuity mistake: In the opening scene Grace goes into the kitchen area and unpacks a brown paper bag. When Will goes to use the coffee pot, the brown bag is on the counter behind the kettle. But in the next shot the bag is in a different position, sitting on top of the kettle. (00:01:10)
Continuity mistake: When Grace opens the cardboard box that has the blue blanket in it, the lid on the box repeatedly changes from being at a straight horizontal angle (fully down) to being up and angled diagonally, as if not pushed open all the way to the fold. (00:09:20)
Answer: The director, James Burrows.