When Sarah (Lacey's character) is decorating the Christmas ornament, it goes from being just being painted white at the top to being painted red and green, with white pearls.
When Ben & Sarah are outside at night in the snow, he helps her put his gloves on. They put on the right glove first, then they start putting on the left glove. The camera angle changes and they are again putting on the right glove (and the left one is on already).
Ben is out in the driveway and claims that he had to shovel because the snow plow was unable to get to the Inn that day. Obviously the writers/directors have never lived in a place that gets snow. He would never be able to shovel down to bare ground, let alone a gravel driveway - which would end up with all the gravel being piled up with the snow.
When Sarah and Jasper are outside in the snow, Sarah is holding the photograph for several minutes while it's snowing. If it were really snowing, the photo would be getting damaged because it would be getting wet.
When Sarah receives her invitation in the mail in Brooklyn, it which is forwarded from Seattle, it is already open i.e. unsealed.