Continuity mistake: Spector is sitting eating breakfast at the assessment centre, when another patient joins him sitting opposite him at the table. The camera then cuts back to Spector and there is a 3rd chair to one side, which Spector is now sitting on.
Dark Descent - S1-E1
Continuity mistake: Stella is talking with Jim Burns at his home about her theory of a delay between murders, and why Paul took so long to strangle his victim. During most of the scene Jim's hair is parted on the left. At the end, as she is leaving, it is on the right.