Revealing mistake: When Prue talks about her relationship with Justin near the beginning of the episode, she says that she finds him to be very predictable, lacking in mystery or "savoir-faire." That doesn't make sense, though, as "savoir-faire" means "know-how." She probably meant "je ne sais quoi," that is, "I know not what."
Revealing mistake: When Prue is practising using her powers while astral projecting, when Phoebe walks away to go see her in the attack you can see the makeup they used in an attempt to hide her tattoo on the right side of her back. It looks as though she's been bruised there. (00:00:43)
Revealing mistake: During the search for the Dragon and teenage Prue, Phoebe's wearing a red top and red jacket, but when Phoebe lands on the ground we can see the bulky beige material of the stunt vest at her back, under the red top and jacket. (00:34:05)
Revealing mistake: The sound of Phoebe writing with a permanent marker was added in, as you can see that the marker never touches the paper. Then after a few seconds Phoebe stops writing to listen to Prue and her marker isn't moving but the sound of writing can be heard. (00:05:30)