Siren Song - S5-E4
Revealing mistake: When the Siren is being healed, you can see that she's just holding the pole next to her, when it's supposed to be going straight through her. (00:19:50)
The Importance of Being Phoebe - S5-E11
Revealing mistake: When Kaya throws the knife at Phoebe watch in freeze-frame and you can see that for the shot from behind her there's no knife in her hands. (00:36:10)
Continuity mistake: Phoebe had to touch both Jane and Malcolm for them to be trapped in the painting, so how come she didn't have to touch Piper and Prue for them to all be freed? (00:39:25)
Crimes and Witch-Demeanors - S6-E19
Other mistake: At the end, it shows the Charmed Ones orbing out of the trial, but Chris and Leo never leave. Right after the Charmed Ones orb out, Barbas begins discussing his evil plans with Gideon, so wouldn't Leo and Chris find out that Gideon is plotting against them? After they talk, the camera pans out and Chris and Leo are not there. I guess they just forgot to put in the scene where they leave.
Continuity mistake: Just after Olivia has killed Mr. Montana and everyone goes running up to see what has happened, Phoebe waves to Paige through the window of the Calloway's house which is shown to be right next door to the Montana's house. Earlier in the episode it had been established that they lived across the street.
Factual error: When Phoebe was telling Paige that the energy ball did not come from the other house, Paige says she saw it come through the window. She could not have seen it because she was in the other room and the door to Richard's dad's office was closed.
The Power of Three Blondes - S6-E4
Continuity mistake: When the Stilman sisters are talking about who gets which powers, Margo(the youngest)had her hand by her side, but in the next shot when she talks about Mitzy's (the middle sister) attitude, she has her hand on her shoulder.
Witchstock - S6-E11
Character mistake: Phoebe, who has moved to Hong Kong, tells Paige that she, Paige, was born in the Year of the Ox. But Paige was born in 1977, the Year of the Snake. 1973 was the Year of the Ox.
Power Outage - S3-E7
Revealing mistake: When Astral Prue kicks Leo/Balthazar in the face during the training drill near the start of the episode, her foot misses his face yet he still reacts as if hit.
Magic Hour - S3-E2
Revealing mistake: In the attic when the sisters are talking about the "rutabaga," some of the shots of Piper are reversed, her "broken" eyebrow is on the wrong side.
Continuity mistake: If Leo can't hear the girls call him when HE is underground, he shouldn't be able to hear the girl's call him when THEY are underground and he doesn't know they are at P3 until a few minutes later.
Continuity mistake: Piper says she wants to go to Paris by plane not by orbing, but in the episode "From Fear to Eternity" flying was Piper's greatest fear.
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.
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: 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)
Siren Song - S5-E4
Character mistake: When discussing how best to help Melissa, Piper tells Paige that her birth father was half whitelighter, when he was fully a whitelighter. (00:25:15)
Revealing mistake: The character Ramus (the elder) changes actor when Leo jumps and orbs to get him away from the attack of the Aggressor. The actor's stand-in is visible instead. (00:18:52)
Sympathy for the Demon - S5-E7
Visible crew/equipment: After Paige orbs the potion onto Barbas and Cole absorbs all the powers, in the shot of Barbas getting up from the floor we can see a blue T-mark and an orange T-mark taped to the rug. (00:39:05)
Continuity mistake: After Phoebe tells Piper about the balloon plan, when Piper starts talking about Leo she fills the blender on the counter, and in the two shots facing Piper the white lid is on top of the blender, but in the shot facing Phoebe the lid is gone before she turns it on. (00:19:10)
Continuity mistake: When Piper writes the name "Nell" backwards on the castle window she uses two fingers so each letter is doubled lined, but when the name is viewed from the outside all the letters are single lined. Additionally, after she writes the backwards "N" on the bottom right window, in the next closeup of the swords' pointy ends that window is blank. (00:30:20)
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.