When Claire is looking through the haunting website, the visitation counter switches from 3875 to 3874.
The cash the OId Man hands Luke is not colored correctly and is clearly prop money.
The inhaler Claire puffs on throughout the movie when having trouble breathing has a tan colored delivery system. In actuality, this type of inhaler is used at specific times for overall bronchial and nasal health. The type of inhaler that Claire would have used for stress-induced shortness of breath would have had a different colored body, usually red. One might argue, however, that if Claire had mixed up her inhalers this could have contributed to her passing out or hallucinating.