Factual error: There is a scene near the beginning of the movie when the mist has just begun. A firetruck roars by, and has Caddo Parish Fire Dept. on the side. This movie is set in Maine. Louisiana is the only state with parishes. All others, including Maine, have counties.
Continuity mistake: Near the end of the film when the five of them are in the car, they stop to watch a giant monster walk past, shaking the car. When we see the monster again it is walking away from them, but the telephone cables are still erect - it is clear that these would have been knocked down by the monster.
Continuity mistake: In the opening scene, the wind has blown a tree down toward the house, which is away from the lake. In a following scene the tree has blown down on the boat house, which is toward the lake.