Revealing mistake: Early in the episode the dead body in the barn ever so briefly flutters his eyelids.
Revealing mistake: The man in the motorised wheelchair that Vic talks to is holding an ice cream cone that his dog is licking. It is a fake ice cream cone - none of the ice cream disappears when the dog licks it.
Revealing mistake: The shot of the first clay pigeon that Barlow Connally shoots is the exact same shot as the first clay pigeon that Branch Connally shoots moments later.
Revealing mistake: The shot of the first clay pigeon that Barlow Connally shoots is the exact same shot as the first clay pigeon that Branch Connally shoots moments later.
Revealing mistake: Vic and Walt are walking toward the crime scene in the snow, while Vic is complaining about the job. In a high angle, you can see two tracks in the snow ahead of the actors where they practiced the scene before.
Revealing mistake: After Henry cuts the boy down from the tree, his eyes flicker when he's supposed to be dead (in the closeup of the boy's face).
Answer: This appears to be movie fiction. In real life, a pharmacist could not legally give out confidential patient information without there being a search warrant. Not abiding by confidentiality laws could result in a pharmacist facing legal issues and losing his or her license.
raywest ★