Other mistake: After Piper tells Phoebe to get to know Dex well and fast because it may be the one sign Phoebe can't ignore, Piper ends the family meeting. In the following overhead shot as Piper walks out we can see her reflection in the wall mirror and it shows her long dark brown hair, but the problem is the reflection should be showing the "Jenny Bennett" golden blonde hair instead. (00:05:05)
Visible crew/equipment: While Billie is in the dorm room with her friend, Taylor, talking about the disappearances, when Taylor gets up and stands beside Billie, the pink tape mark (it's a toe box mark) is visible on Billie's seat. (00:07:20)
Desperate Housewitches - S8-E4
Continuity mistake: Paige asks how The Source was previously vanquished, but she was there both times: when the original Source was vanquished, and again when they vanquished Cole. Also Phoebe wasn't actually there for the final vanquish of Cole, but was taken back by Cupid as if it was her memory.
Revealing mistake: While Piper is trying to convince Paige to be at P3 for speed dating, Piper says, "I will resort to whatever I have to, besides you might actually meet someone you like," and after the quick shot of Paige, when it cuts to Leo holding Chris as he's standing in the doorway asking for baby Tylenol, the mirror's glass is green at the right side of the screen - for the special effects editing of the fake reflection. (00:04:40)
Continuity mistake: After the opening credits, while Piper tries to persuade Paige to help with the speed dating at P3, in two shots facing the bed and in the shot facing the mirror showing the "Jaime and Jo Bennett" reflection, the lamp on the far side of the bed is turned on. When Leo is holding Chris he walks past the mirror, and in this reflection that lamp on the far side of the bed is turned off, but in the next shot facing the bed that lamp is on again. (00:04:55)
Continuity mistake: After Antosis and the Imp Master are vanquished, in a following shot we see Phoebe wearing a robe and sitting on the bed, then we see her "Julie Bennett" reflection in the mirror, but notice that even though the style of the robe is the same, the colorful designs are quite different in the reflection. This happens again later when the sisters and Leo are seen in the mirror's reflection, as they undo the spell to reveal their true selves. (00:33:25)
Continuity mistake: When Paige and the reporters interrupt Piper and Leo's argument, Piper's arms move from out in front of her to her sides. (00:32:55)
Visible crew/equipment: When the smoke alarm starts blaring at the manor JD freaks out, and as he runs out of the door the reflection of a crew member wearing shorts is visible on the glass door. (00:23:05)
Continuity mistake: When Paige goes to talk to Henry at the police station, her arms are on her hips in the shot from the front, but down by her sides in the shot from the back. (00:14:20)
Hulkus Pocus - S8-E9
Other mistake: When Piper is explaining to Phoebe that they don't have enough time to save Billie, she lists all the things they need to do ending with "fix us and then fix Billie..." This doesn't make any sense, since when she's saying it there's nothing wrong with them to fix. It's only after she says this that they come up with the plan to infect themselves. (00:29:54)
Other mistake: When The Angel of Death comes to Leo in the car Leo asks him "can I at least see my son again?" which is an odd way to ask that question given that he has two sons.
Continuity mistake: When Paige arrives back at the manor after being stood up by Henry, Piper has both her arms on the table in front of her. Her arms are then crossed over her chest, then back on the table. (00:16:30)
Visible crew/equipment: At the bank, when Nick gets off the phone after talking to his son he walks around the stanchion, and as he says, "I never wanted to hurt anybody," we can see the light green T-mark on the floor where he had been standing. (00:29:15)
Visible crew/equipment: After orbing into the manor's attic Paige reveals to Rohtul that she switched identities with Billie, then when the real Billie walks out and joins the sisters, we can see the pink T-mark at the bottom of the screen. (00:39:35)
Repo Manor - S8-E13
Other mistake: When Piper blows up the dollhouse, killing Pilar, Phoenix and Patra, you can hear the sound effect of telekinesis, despite Piper's power being molecular combustion.
Continuity mistake: Season 8, Episode 14, "12 Angry Zen": When Phoebe finds Paige at the manor after the demon/Zodiac fight, Paige rubs her neck with her left hand. In the next shot, it's suddenly her right hand on her neck. (00:28:55)
Visible crew/equipment: When Piper is coming down the stairs with the staff, if you look in the top left corner of the stairs, you can see a piece of camera equipment moving.
The Last Temptation of Christy - S8-E15
Visible crew/equipment: At the start, Piper tells Billie she needs to be patient with Christie, and when Piper adds that if Billie needs anything they are just a call or an orb away, the pink tape mark is visible on the floor at Billie's feet. (00:01:10)
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.