Factual error: When Dexter is punching Olivia's father in his left side, he says "That's your liver." Only the liver is on the right side. For a serial killer who routinely dismembers bodies, Dexter should know which side the liver is on. (00:42:50)
Revealing mistake: When Dexter stomps on Barry's kidney, you can see his foot doesn't even make contact with Barry's body.
Answer: No, Harry is not the real father. While he did have an affair with Dexter's biological mother (Laura Moser), this was when she was his C.I. Dexter was already born at that point.