Audio problem: Just before Dorothy has her operation, Mike is seated at her desk looking through her medical books. Sully pays a visit to comfort her. During their moment, you can hear slight foot shuffling from the camera crew in the foreground - which is not coming from the outside. Also, you hear a slight grunting during a pause in their conversation.
Visible crew/equipment: Loren wakes Dorothy in the middle of the night to mention selling the store and taking her on a trip to New York. While seated at her bedside, you can see shadows of a crew member on the bed pillows next to her, and hear some muffled foot movement while Loren is seated, talking to her.
Other mistake: In the scene where Dorothy decides to join the church picnic (just before her operation) Grace is talking to her and hands her a glass of cider as Robert E. approaches. The sky is partly cloudy, but the lighting changes slightly during the shot, and at one moment, appears too bright on Dorothy just before she sets the glass down and walks away.
Visible crew/equipment: When Sully visits Mike at the clinic, after dark, to console her over Dorothy's health condition. Watch as he moves past the window. You can see two control room blue screens in its reflection, alongside a boom mic, and the shadow of a long-haired crewman, who stands up, and then sits back down. Though the camera moves behind a potted plant on Mike's desk to conceal it all.
Answer: A Cooper was someone who made various things out of wood including wooden caskets and even barrels.