Show Ghouls - S7-E15
Plot hole: When Leo tells Piper that he believes he found the demon Sargon in the Book of Shadows (which may be the demon Count Roget made a faustian deal with), Piper looks at it and says that they vanquished this demon five years ago. Which would've meant they vanquished the demon with Prue. When in fact the only demon that happened with was Zahn in season 6 episode 6, "Soul Survivor," and they did that with Paige.
Continuity mistake: After Leo rescues the driver in Texas, when it cuts to the manor Phoebe is wearing a pair of white gloves which she takes off and puts in her pocket, but when Phoebe insists she will not save another innocent until she finds out what happened to Leo, Phoebe is wearing both gloves again. (00:07:45)
Continuity mistake: When Piper is talking to Cole, they show the other Piper on the couch. Whenever you see Piper talking, you can see that the other Piper's legs change position throughout the shot. They go from being straight to both legs bent to one leg bent to straight. (00:18:00)
Continuity mistake: In this episode, Phoebe told Drake that she "can't believe it's been three weeks already", but Drake said in "Carpe Demon" that he only had two weeks to live.
Little Box of Horrors - S7-E18
Continuity mistake: When Paige complains about the ringing in her ear, she's rubbing her temple with her right hand and holding a coffee mug with her left. In the next shot, which is cut too fast for her to have moved, the hand on her temple has jumped to holding the coffee mug. The mug has also jumped to in front of her mouth. (00:01:45)
Little Box of Horrors - S7-E18
Character mistake: Katya (as Nina) says that Pandora's Box is "a gift the gods gave to Prometheus." But the Box was given to Epimetheus, not Prometheus. Epimetheus ignored the warnings of Prometheus, his brother, and accepted Pandora herself, who bore a box, as a gift from the gods.
Continuity mistake: When Paige is complaining to Leo about not having time to take on a charge as a Whitelighter, she rests her head in both of her hands on the kitchen table. In the next shot, her head is only resting on her right hand. (00:00:30)
Other mistake: In both scenes in which Phoebe's hair is cut, her hair is up, with very little loose hair. There is no way that the amount of hair shown to be cut in both scenes could have come from her head. In the first scene, it is very clear when the demon cuts her hair, it is a few tendrils, yet when he is shown with Imara, it is a very measurable amount of hair. The super speedy guy who cut her hair the 2nd time, when she was Imara, was too quick to see the actual amount cut, but again, because of her hairstyle, he could not have cut the amount he shows to the Charmed Ones in the next scene.
Other mistake: When Paige is talking to her charge in the club the same guy walks behind them twice in the scene. (00:14:00)
Continuity mistake: In this episode they say an alchemist has the power to control the dead but not bring them back to life. However, in the season three episode "Coyote Piper," the alchemist brings both the body in the alley and Piper back to life.
Continuity mistake: When Paige is at the bar with her newest charge we see the same extra walk by 3 times, going the same direction each time.
Something Wicca This Way Goes - S7-E22
Continuity mistake: When Zankou is looking at the spell in the Book to steal TCO powers we see that it is the same spell Aunt Gail used in "How to Make a Quilt out of Americans", except that in that episode she ripped the page out of the book. It shouldn't be there for Zankou to use. (00:09:56)
Something Wicca This Way Goes - S7-E22
Visible crew/equipment: When Agent Keyes enters the manor and walks into the kitchen, just as the hazmat team tells Keyes it's OK to breathe the air, the red tape mark is visible on the floor in front of Keyes' feet. (00:37:00)
Something Wicca This Way Goes - S7-E22
Continuity mistake: Phoebe's shoes change between shots. Near the end, while fighting Zankou in the basement, he hurls the sisters to the ground and Phoebe is shown wearing sandals. When she stands up, she is now wearing sneakers.
Something Wicca This Way Goes - S7-E22
Continuity mistake: Tim's eyes keeps changing from opened to closed at the morgue with Zankou.
Something Wicca This Way Goes - S7-E22
Continuity mistake: The hole where the demon throws an energy ball through the roof is gone when the doors close.
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)
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.