When Mr Mortimer comes to the Stephens household ,after his trip with Samantha to the North Pole,there is no snow in the front. When they pan to the living room,there is a lot of snow in the back yard.
In the teaser, Samantha is deciding where to put the Christmas tree. When the tree is sitting where the TV stood, she motions for the tree to move to the corner (offscreen) by the front window. On the next cut, the tree appears by the door to the patio. It's likely that showing the tree in one more location was cut for time.
Mr. Mortimer gives Darrin 10 seconds to change his mind. This actually takes 16 seconds. His 5 second threat to Samantha to leave his house actually takes 11 seconds.