When Prue and Piper are about to punish the dogwalker in the end of the episode, they're all standing in the window. Phoebe says something like, "Hopefully now he won't [start a chain of events that ends with Phoebe being burned alive]." She then exits to the left side of the window. Therefore, from inside the manor, she should be on the right side of the interior window. But when the camera cuts to the inside, she's on the left side of the window.