Factual error: There is no way cops would just walk up and open fire on a suspect unannounced, not knowing if he is armed or not, and with an innocent bystander so close.
Revelations - S1-E10
Continuity mistake: When Piper reveals herself as the killer in the dock, you can see her dropping the mask and shortly after, removing her poncho and drop it on the floor as well. In the next shot from the side of the dock where you can see Piper and Emma face to face, the mask and the poncho are no longer on the floor. (00:32:20 - 00:33:10)
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.
Revelations - S1-E10
Other mistake: At the end after Piper is dead and the ambulance is there, Emma is bandaged over the top of her clothes.
Continuity mistake: When Brooke gets a text from the killer posing as Brandon, she has an iPhone 6, however close up shots of the phone are a different model. (00:28:45)
Continuity mistake: When Noah and Emma enter the bowling alley, Noah has a backpack. In one cutscene, he doesn't and it then reappears.
Continuity mistake: When we first meet Billie and after she says that they "don't give tours of the murder house", some hair hanging down the right side of her face constantly tucks itself behind her right ear and back again between shots.
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.
Continuity mistake: When Emma and Audrey enter the barn, finding the scythe used to kill Jake, the scythe moves position on the ground several times between shots.
Audio problem: After talking with Kieran near the start of the episode, Emma (off-screen) gets into her car, shuts the door, turns on the engine and starts driving away in 3 seconds flat.
Continuity mistake: When Eli tries to cheer up Emma, the house they arrive at has a sign outside that says "Wren Lake Estates Sales Office." A few minutes later, there's an exterior shot of the house and the sign suddenly says "Wren Lake Estates Model Home." Once the house catches fire, the sign says "Sales Office" again.
Other mistake: When Deputy Dwayne is talking to Sheriff Miguel Acosta while Acosta pours himself a cup of coffee, he picks up the coffee jug, pours his coffee and puts the coffee jug back far more quickly than is humanly possible.
Continuity mistake: When Brooke hugs her dad after putting on the cheerleading outfit, she puts her arms around his neck in the wide shot. But in the close-up shot immediately afterwards, her arms are no longer around his neck.
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.
Continuity mistake: When Emma, Audrey and Brooke are talking in the bathroom, Audrey's hair keeps moving position between shots.
Other mistake: In the third scene, where Emma is texting Kieran, the time stamp on the text reads 3:32 PM. She then goes downstairs where her dad is waiting and says she's "late for school." If that timestamp was accurate she'd have missed almost all of school.