Revealing mistake: Before Jason Dean is shot outside the penthouse, Phoebe is waving her hands trying to convince him that the world is not real and you can already see blood on her fingers.
The Power of Three Blondes - S6-E4
Revealing mistake: When Phoebe is thrown out of the Bay Mirror office by a security guard, Alyssa Milano's stunt double's face is digitally blurred.
Revealing mistake: As Phoebe and Rick are in the car about to do the robbery, she pulls out in front of the armoured van and as she drives out onto the road you see Phoebe's stunt doubles face.
Revealing mistake: When Piper is being spun in the web, she spins around and gets stuck to the wall. If you look closely Chris's eyes look above the CGI figure and do not follow it correctly.
Revealing mistake: In Chris's flashbacks, it's supposed to be the day he left to come to the future. But his hair is longer than it was in the season 5 finale when he came to the future.
A Wrong Day's Journey Into Right - S6-E20
Revealing mistake: Right after Paige is orbing out, the camera is on Phoebe and on her right, you still see Paige's shoulder. And then it cuts to Paige orbing back in.
Valhalley of the Dolls (1) - S6-E1
Revealing mistake: When the sisters summon the Trok demon Phoebe is wearing a bikini top, and as the demon blasts them all backwards into the wall, Phoebe is wearing something around her waist for the stunt. (00:07:20)
The Courtship of Wyatt's Father - S6-E16
Revealing mistake: Just after Piper and Leo are taken away, Paige orbs down to the ground and runs up to Pheobe, places her hand on her, and shows a blood-covered hand showing that Pheobe's been injured. But before it's shown, while Paige is running up to Pheobe, you can see Paige deliberately keeping her hand closed and facing away from the camera, because it's already there when she orbs down.
Answer: That was a mistake in the series.
Also, the episode is called 'Babies First Demon' and this alone tells us that it's Wyatt's first time in the field (so to speak) and as the sisters say, they've done a good job of clearing up their own magical messes so far. Nobody really knows how advanced Wyatt's powers are, or will become. That's why the cleaners appear, to nip things in the bud. The Cleaners didn't want to chance that the sisters could clean Wyatt's magic up, just incase they couldn't. Therefore intervening themselves, just in case.