The inscription on Holly's snow globe changes fonts between shots.
In the scene when Doug (Ryan) and Ted play football and fight, there are green leaves on the trees. That is supposed to be during the Christmas/new years season. All the leaves should have been gone. Also, later on in the movie, he is driving around in a convertible with the top down when there is snow all over.
The establishing shot of young Holly's house on Christmas morning, show lush and leafy trees, which should have been barren at this time of year.