Factual error: When printing the image of the painting, Stella uses the printer driver "Microsoft XPS Document Writer" - which would save the output to a file. However, she still gets a printout from the printer in the office. (00:02:30)
Suggested correction: Microsoft XPS Document Writer creates a document in XPS format then prints said document. I use it at work. It works in the same way as "print to PDF".
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.
Visible crew/equipment: When Glen Martin escorts Paul Spector into a car, a camera is reflected in the car's window. (00:34:00)
Other mistake: When Spector is sitting up with the help of his nurse, the subtitles say [Spencer groans]; I think they mean "Spector", and he was the only man in that scene. It makes sense that he was grunting while sitting up.
Factual error: Superintendent Gibson wears her Metropolitan Police uniform to the press conference. She is wearing a tie, but female officers in the Met instead wear a black and white cravat.