Continuity mistake: After Strax hits Clara with a newspaper she comes downstairs and he asks her if she needs anything. She asks for water and he places the bucket of mop water on the table in front of Clara. They have a conversation about the water and at the end of the conversation Clara looks at her newspaper and the bucket has disappeared from the table in front of her. Neither of them moved it. (00:26:45)
Continuity mistake: After the Doctor is knocked unconscious, Clara uses the psychic circuitry to pilot the TARDIS to what turns out to be a moment in the Doctor's past, in the barn first seen in "The Day of the Doctor." The loft in the barn where the young First Doctor is sleeping in bed, however, was not present in the previous episode.
Factual error: Near the end of the episode, the full moon is shown in the daytime sky, well above the horizon. This is impossible, as any celestial body lit by the Sun has its full phase only when it is directly opposite the Sun; thus, a full Moon rises at sunset and sits high in the sky only during the night. For the Moon to be in the sky during the day as shown, it would have to be visibly of a phase other than full.
Continuity mistake: When Clara tells Maisie that "Difficult people can make you feel all sorts of things", as she finishes the sentence the view cuts from a close-up of her to a wide shot, and the light and shadows cast onto her face change with it. (00:17:20)
Continuity mistake: In the restaurant basement, while the Doctor and Clara are looking around while speculating on why the clockwork droids are harvesting organs, Clara moves a chain out of her way with her left hand before releasing it, only to be holding the chain again in the next shot. (00:44:10)