Revelations - S1-E10
Revealing mistake: When Kieran looks at his phone in the car, the image of Emma calling him is upside down. The image was added after the filming was done.
Revealing mistake: When Sheriff Miguel Acosta answers his phone right before he finds the mask in Gustavo's room, he doesn't actually answer the call, and his phone is still in call mode when he raises it to his ear.
Revealing mistake: Right before the police arrive at the barn, one of the prongs on the pitchfork that Emma is holding wobbles as if it was made of rubber.