Someone to Witch Over Me - S7-E7
Continuity mistake: When Paige talks to agent Brody at his apartment, her hair moves from covering her shirt straps to not, then covering them again. (00:09:45)
Someone to Witch Over Me - S7-E7
Visible crew/equipment: After Paige's guardian angel is snatched by Sarpedon, when Phoebe rushes out of the kitchen to find Paige lying on the floor, two long white tape marks are visible on the floor to Paige's left and right. (00:16:15)
Someone to Witch Over Me - S7-E7
Continuity mistake: In episode 7-7: "Someone to Witch Over Me," Piper is killed by the demon Sarpedon's metallic claw. When the claw strikes her, she falls back with her arms behind her, landing partially on her palms, allowing her to complete the fall by sinking gradually to the ground. Then there is a cut to a closer shot, and we see her fall again. The second time, she falls directly into a more prone position with her arms raised and the backs of both hands facing the ground.
There's Something About Leo - S7-E9
Continuity mistake: When Leo is preparing to tell Piper that he's an Avatar, Piper has an orange bowl in her hand and sets it down on the table. In the next shot, she's holding the bowl again and sets it down a second time. (00:17:45)
Visible crew/equipment: While Leo and Piper are at the photography studio with their kids the Avatars appear, and in the shots facing the Avatars the red tape mark is visible on the floor, in front of Avatar Alpha. (00:01:10)
Continuity mistake: Midway through the episode, the Seer is looking through the sisters' photo album. Several of the photos actually include everyone who was present for the events depicted, leaving nobody to take the photo. And since the events were shown in various episodes, we know that no photo was taken at those times by any automated method.
Plot hole: The innocent who gets Piper's powers uses them to freeze Piper and Phoebe. But even though Piper and Phoebe no longer have their unique powers, they are still good witches; they were still able to scry, and we have encountered good witches on the show in the past who had no powers at all. And by the rules of magic within the show, good witches do not freeze.
Continuity mistake: In the second to last scene where Piper tests her powers on the lamp and Phoebe is cleaning, you can see Piper's bra strap when she blows up the lamp but when she turns to face Phoebe its covered. Through out the scene it's covered and exposed without her ever adjusting her shirt.
Plot hole: When the man and woman receive Piper and Phoebe's powers, the lady freezes the man and Phoebe due to fear, but good witches don't freeze, so if Phoebe froze (which she shouldn't have due to only her active powers lost) then why did the man? If he had Phoebe's powers then he isn't mortal and therefore should not freeze.
Extreme Makeover: World Edition - S7-E12
Deliberate mistake: While Beta, Leo, and the sisters are walking through the sleeping city Paige notices someone in a "bad suit" moving, and as she walks over we can see a bit of the white writing on the SUV's spare tire cover, at the left side of the screen, but when Paige declares she's not paranoid that white writing has been edited out in this shot. (00:26:00)
Other mistake: In the kitchen scene, Phoebe adds a mix to a pie crust but puts an empty crust in the oven. (00:04:10)
Deliberate mistake: When Zankou and the Charmed Ones force the Avatars to "put the world back" by rewinding time, in the first shot of people waking up note the Jeep in the backround. The problem is the words "Jeep Liberty" are on the spare tire cover in this shot, but in the previous episode "Extreme Makeover World Edition" that spare tire cover is all black because those words were edited out in two shots. The first shot is when that group of people fall asleep, and second shot is when they all wake up the first time. (00:35:15)
Plot hole: When the Avatars agree to rewind time they say that they can either put the world right or save Brody but not both. This doesn't make sense since they're rewinding to right when they put everyone to sleep, which is before Brody was killed.
Other mistake: When Phoebe gets the premonition to see all the loss, she sees the scene where Piper dies in All Hell Breaks Loose. Since time was rewound this event never happened in this timeline, and we're never given any reason to believe Phoebe would know this happened after the time reversal.
Carpe Demon - S7-E14
Revealing mistake: After Leo's meeting on the bridge with two of the Elders, it cuts to Phoebe walking down the stairs as she catches Drake dancing, and when he approaches Phoebe to take her hands, the top of the set with lighting can be seen in the dining room.
Carpe Demon - S7-E14
Revealing mistake: When Miss Donovan is chained up, it is very obvious that her hands can easily slip through the shackles.
Show Ghouls - S7-E15
Continuity mistake: When Phoebe is on the phone with Elise about the Cosmo interview, she jumps between shots from leaning over the kitchen table to sitting straight up. (00:05:45)
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.
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.