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)
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.