On Christmas eve Alicia's hair changes frequently from wavy to curly as the night progresses. It seems to get curlier as it gets later.
At 1.14 in, when Missy is outside in the car talking to Drew on the phone, the bracelet is clearly on her right wrist. Once inside the house the bracelet is now on her left wrist and stays there for the duration of the movie.
The tree that they buy at the lot, the one that they drive home with isn't nearly as tall as the tree that they decorate in the house.
There are no mountain ranges, such as the one depicted, within hundreds of miles of Chicago. However, it's possible that Drew, with his resources, "whisked" the family away to Colorado for the day.
Despite the fact that Drew says his father left his mother when he is four years old, and that she worked as a waitress at a diner to support them, it seems that Drew and his mother continued to live in the fairly large house depicted in the film, until he was much older.
When Drew and Tom walk up the stairs to go see the play the sign misspells Lincolnwood as Lincoln Wood.
When Drew tells Alicia that his father abandoned the family when he was four years old, it could be possible his mother received the house in the divorce settlement, but worked at the diner as a secondary job to supplement her income in order to afford living there.