Continuity mistake: The sunglasses Nancy placed near the center right side of her yellow legal pad changed positions a couple times with camera shifts. Initially, the left lens was almost touching the legal pad and the right lens was at about a 45° angle. Seconds later, the sunglasses were further away from the legal pad. Next, the sunglasses were close and parallel to the legal pad, not angled. (IF Nancy had accidentally bumped her sunglasses with her elbow, they would have been pushed away from the legal pad). (00:18:02 - 00:18:30)
Continuity mistake: The height of the stack of magazines on the coffee table in front of John changes with the camera's view. Front views of John show a high stack of maybe 15 magazines. Side views of John show a much shorter stack of several magazines. (00:25:03 - 00:26:07)
Continuity mistake: The way Franck's scarf was wrapped and tied around his neck changed from when he was sitting on the steps (wrapped around a few times with ends folded under) to when he was standing along the guard rail (a loop down the middle of his chest). (00:15:09)
Continuity mistake: Ed Harris plays a property manager character and is featured in the beginning of the movie, walking with a pronounced limp, a seemingly painful gait. His character is shown in many other nominal scenes throughout the movie without limping. Most notable, shortly before the end of the movie, his character is shown dancing wildly, spastically, and jumping to music, seemingly unencumbered and fluidly, in a way that his character in the first part of the movie would not have been capable of doing.
Continuity mistake: Audrey is driving straight along the kerb before coming to a stop in front of her house. When Molly is getting out of the backseat, the Jeep and another vehicle are directly behind Audrey's rear bumper, which blocks her approach. (00:59:45 - 01:00:06)
Continuity mistake: When the "kid" rolls off his sled into the snow, his sled is right behind him and about to hit the leg he was turning over in the air, but an aerial view shows the sled's tracks stop about 10' before the kid. In the aerial view, the sled is facing and headed toward the cliff, not ending up perpendicular to the cliff as the ground view show. Also from the aerial view, when the "kid" turns his leg around in the air, the sled is already stopped above, not about to ram him. (00:02:50)
Continuity mistake: Samantha placed the bottle of glue on top of the metal object she glued, but the bottle of glue was on the desk and the metal object was gone when the doorbell rang. (00:04:56)