I've Got You Under My Skin - S1-E2
Continuity mistake: In the previous episode, Piper tried out for a job as a chef at a restaurant called "L'Opera Ristorante" and was hired by Chef Moore. Then in this episode, she works at a bar and restaurant called "Quake," but she talks about Chef Moore quitting and leaving her in charge of the establishment, so it's not meant to be a different place.
I've Got You Under My Skin - S1-E2
Continuity mistake: When Phoebe flirts with Alec at Quake, she rests her head in her hand. In the following shots between Alec and Phoebe, her hand moves back and forth from her face to the tabletop. (00:02:00)