Continuity mistake: It was snowing relatively heavily during the Baxters' drive to the Christmas party. Right before Catherine called to check on the kids and told Alexis "it's really snowing up here", an external view of the house did not show any snow falling. (00:38:15 - 00:38:42)
Continuity mistake: The vent cover in the upstairs bathroom looking down into the wine cellar is different compared to looking up to it from the wine cellar plus the two views cannot be of the same vent. In the upstairs bathroom, the vent is white (or off-white), is low on the wall (which is also white), and has a more elaborate design. Looking up from the wine cellar, the vent is blue, on the floor/ceiling, and has a simpler design. (00:50:25)
Continuity mistake: The driveway is clear of snow the day the Baxters move in. Based on the amount of snow in Mason's yard (across the street) and other outside views, there has not been a snowstorm after the Baxters have settled. In fact, the wet roads and melting snow on lawns indicate an ongoing thaw. Christine (Finn's mother) tells the kids they will be leaving to go shopping for a tree and decorations as soon as Curtis (Finn's father) finishes clearing the driveway. Curtis is then shown struggling to use a snowblower to remove A LOT of snow from the driveway (which had been clear of all snow on move-in day). (00:00:58 - 00:18:51)
Answer: Simple answer is because ABC Family along with Fox TV Studios produced the movie specifically for their television audience. Which is what they did for "Home Alone 4" as well. Airing original movies on a channel is a way for networks to increase ad revenue as it draws an audience to watch their movies. They wouldn't have a need (and probably not a budget) to release it in theaters.
Bishop73