When Jared shows up at Emily's house and convinces her to go to the HOA meeting, she's in her pajamas with her hair in a ponytail. In the next shot where they're still on the same walk, her hair is down and styled.
When the storage room, the mountains in the background go back and forth from snow covered to little to no snow.
Pamela says she moved to the street five years ago. When Emily is going through the photographs she took as a kid, there is a photograph of Pamela.
During the opening credits, when Emily is carrying a bunch of wrapped presents, a package with silver Santa paper is on top of a blue one. The next scene she is seen from the back ascending stairs, and the blue package and the Santa package are the same level.
When making the snowmen, a snowball fight breaks out, and Ned moves the ladder. The ladder moves back on its own.
The snow men in the snowman contest are so obviously not real snow. They are too perfectly round. And the snow holding them together is not snow.
The morning after Emily and Pamela figure out the snowman building contest, there's a daylight scene where a speck on the camera sensor is visible throughout.