Factual error: When Roy is electrocuted and falls from the roof, after Karen uses the defibrillator paddles on Roy, she lifts both paddles, looks at the EKG monitor and says "He's converted." How exactly could Karen have known that he's converted? It's impossible for the EKG monitor to show anything at all. Either the defib paddles have to be in contact with Roy's body for the "quick-look" to get a reading, which they weren't, or the ECG electrode discs have to be on Roy's chest connecting him to the EKG monitor, and they weren't. As an aside, just watching Marco having problems attaching the air mask, and quickly glancing up towards the camera frustrated, then giving up is priceless.
The Chalice - S2-E3
Factual error: After the opening credits, Caine is walking along the beach. On the beach behind him, you can see a modern long-board surfboard lying in the sand which gets caught up in a wave.