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.