Something Wicca This Way Comes - S1-E1
Continuity mistake: When Piper and Jeremy are in the elevator, he pulls a knife on her she freezes him. When the camera shows him from her p.o.v he has this really "snarling" looking face with his mouth open. But when the camera changes the shot from looking at them from outside the elevator, his face is completely different and his mouth is almost closed.