Plot hole: If the Lady of the Lake walks every night to her room and kills those in her path, why didn't Flora and Miles' parents die in their room by the hands of the Lady in the Lake when they first moved in?
Factual error: The phone in the manor kitchen uses a single ring common to North American phones, not the double ring used in Britain.
Factual error: The show doesn't seem sure what Henry and Dominic's titles are. Dominic is referred to as both Lord Wingrave and Mr Wingrave (and his wife as Lady Wingrave). Henry is referred to at various times as Lord Wingrave, Lord Henry Wingrave, Sir Henry Wingrave and Mr Wingrave. Dominic is the elder brother, so if the title was inherited only he would hold it. When he dies, it would pass to his son, Miles, not his younger brother. If they held the titles as younger sons of a duke or marquess (although there is never any indication that they have an elder brother, so this seems unlikely) then they would be Lord Dominic and Lord Henry, not Lord Wingrave. In neither case would they be addressed, especially not by their staff who would definitely know the correct form, as Mr Wingrave or Sir Henry.
Continuity mistake: Hannah's outfits don't match when she follows Miles into the Chappelle after she finds him smoking. She goes in wearing red and once she enters they show her wearing green. (00:24:16)
