As Claire wonders where all the neighbourhood children are, and suggests that perhaps they are all going out later this year, Alex points out that the street is full of kids. When the camera pans outside it is clearly dark outside (as one would expect during Halloween). However during the indoor shots when Alex and Claire are speaking, the room is brightly lit with natural sunlight, and Alex's glasses clearly reflect the sunny window she is looking at behind the camera.
When Claire is hiding in the bathroom; Phil and the potential buyers walk in and can not see her. When they leave the bathroom and Phil closes the medicine cabinet you can see Claire standing in the tub reflected in the mirror. The mirror is in line with the door and they all would have been walking into the bathroom with nearly the same view as the mirror and should have seen Claire standing there. The woman was standing right in front of where Claire was supposed to be in the tub, and even if she hadn't seen her when she walked in she would have seen her once she was standing in front of the sink.