Plot hole: When John retrieves the mail from the postman, Iris dashes outside. Less than 10 seconds after she closes the door, a car is heard, off-camera, honking a horn. Wouldn't John have found Iris so soon after that noise is heard? She doesn't seem to have enough time to allow for a search for her.
Character mistake: Near the end, Iris's doctor attempts to take John's pulse. He has his hand wrapped around John's hand, his fingers nowhere near the top of the wrist, where the artery is; and as he counts the "beats", against his wristwatch, John talks to him and he talks back - when you are counting something, you can not talk at the same time; you lose count every time.