Revealing mistake: When the pawn shop owner jumps through the glass door, it is painfully obvious that it's a stunt double.
Visible crew/equipment: When the sisters hide the chimps in the laundry cart to slip out of the hospital, the blue T-mark is visible on the floor at the bottom of the screen, before they peek around the corner and notice the TV. (00:20:15)
Continuity mistake: Near the end of the episode Piper is talking to her sisters in the parlor with her watch is on her left wrist and a bracelet on her right wrist. She goes upstairs to her room to cry and her bracelet and watch have switched places. (00:39:05 - 00:40:00)
Revealing mistake: When Phoebe punches Dr. Williamson, it's easy to tell that she doesn't really punch him.
Be Careful What You Witch For - S2-E22
Visible crew/equipment: While Leo is up in the attic with Piper, flying Phoebe, and teenage Prue, Leo explains what happened to Prue, and when Phoebe asks how it's even possible, we can see the stunt harness at the back of Phoebe's jeans as she rises in the air. (00:18:45)
Be Careful What You Witch For - S2-E22
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)
Be Careful What You Witch For - S2-E22
Plot hole: When teenage Prue has run away with the demon, and Phoebe and Piper find her in the park, teenage Prue is 'killed'. Her sisters drive her home to get Leo to heal her, but shouldn't they have just been able to call to Leo to orb to them when Prue was first hurt, and heal her in the park, and save driving back to the Manor, risking Prue dying?
Suggested correction: I see orbing to the park but he didn't heal her, she was already dead and he can't heal the dead, that's why the genie brought her back - that's what Phoebe wished for.
But if they would have called for him right away - he would have been able to heal her before she died. However at this point in time I don't think they knew how to call for him.
Be Careful What You Witch For - S2-E22
Continuity mistake: When Piper and Leo confront the genie at the restaurant, the genie is eating food as fast as he can. At one point he gets a line of pasta sauce on his cheek. The shot changes, then goes right back to him only now the sauce is gone with no time for him to have wiped it off, especially since his hands are full of food.
Be Careful What You Witch For - S2-E22
Continuity mistake: When Phoebe and Piper are leaving to go get Prue, Piper kisses Leo on the cheek and there is a lipstick mark on his cheek. Then the shot goes to Piper then back to Leo, and the mark has gone with no time for him to remove it.
Be Careful What You Witch For - S2-E22
Continuity mistake: At the end of the episode, when Prue shuts the door magically it shows the inside of the house. There should be a doorway parallel to the front door that leads from the foyer into the dining room, but instead there is a wall.
Be Careful What You Witch For - S2-E22
Continuity mistake: When Piper and Leo find the genie at the restaurant, look at the girl in the background, when Piper freezes the time, first she's talking to someone, then she's looking at a menu.
Be Careful What You Witch For - S2-E22
Other mistake: Phoebe says to the genie "you've been stuck in the bottle for 200 years?" Later the genie says he will be an unwelcome house guest and not put the CD's back in their case. If he was in the bottle for 200 years how would he know of CD's?