Plot hole: Ep 6 Ffion, with backing by a squad of police, is in a frantic search to find the killer's latest victim. She finds something and calls into headquarters, whereby the DCI says, "I'll send backup." She already has a swarm of police aiding in the search.
Character mistake: Stella goes to the hospital to inform her daughter Sam about Hope dying. During the conversation, Stella calls her daughter Samantha and later on calls her Sarah twice.
When You Know, You Know - S2-E7
Continuity mistake: Morgan's wedding veil goes from front to back multiple times in the same scene. (00:09:32)