Continuity mistake: When the ani-men break into the manor the entire large center glass of the left door ends up broken, but later while Phoebe is looking for the hydrogen peroxide, Prue notices the front doors and the left door's center glass is intact with only the bottom corner broken. (00:22:00 - 00:27:05)
Continuity mistake: After the manor is broken into, in the following shots while everyone is in the foyer the left front door is wide open in most shots, but in some other shots both front doors are closed during this scene. (00:21:50)
Continuity mistake: After class, when Phoebe is talking to her study group she pulls out the flyer for P3, and in the first shot the flyer is in Phoebe's right hand, but in the next shot she's holding it out in her left hand. (00:01:40)
Continuity mistake: When Leo comes to the manor to tell Piper about Masselin, during the conversation Prue is not wearing her choker in the shots facing her (with her arms crossed) and Phoebe, but in the next shot when Leo tells Piper that he knows she's upset we see Prue's choker suddenly around her neck. (00:11:50)
The Wendigo - S1-E12
Continuity mistake: When Andy is lying on the ground unconscious The Wendigo rips open his shirt popping all the buttons, but in the closeup of Andy's face his shirt is still buttoned up. (00:38:50)
Which Prue Is It, Anyway? - S1-E16
Continuity mistake: While Phoebe explains the slam man training system Piper puts on Phoebe's boxing gloves, and when Prue says that demons don't play fair Piper playfully raises her left arm to Prue's forehead, but in the next shot facing Prue it's Piper's right arm that's raised. (00:04:00)
Continuity mistake: While Andy and Darryl are at the station talking about why Andy's been "walking around...like a zombie," Andy places a pencil behind his ear, but when it cuts to Inspector Blakely walking in behind Andy the pencil has vanished between shots, but it reappears again in the next shot. Then when Andy borrows the photograph of the knife, once again the pencil vanishes between the closeup and wideshot. (00:09:10)
Love Hurts - S1-E21
Continuity mistake: When Prue shoots the Darklighter arrow at Alec, he orbs out and the arrow sticks into the wall behind him. In the next shot, the arrow has disappeared. (00:25:45)
Continuity mistake: At Phoebe's high school reunion, the gym teacher holds out a name tag in her left hand, but then Paige takes it from her right. (00:07:50)
Witchstock - S6-E11
Continuity mistake: When Chris orbs Phoebe from Hong Kong, Phoebe raises her arms to hug Piper twice. (00:00:50)
Continuity mistake: When Anling unmasks Yenlo, Yenlo's left hand is covering his wound. In the next shot, his hand is down by his side. (00:03:50)
When Bad Warlocks Go Good - S1-E18
Continuity mistake: When Brendon is about to sacrifice the young woman he has the tip of the dagger touching her chest in one shot and in the next shot, when Prue breaks open the door, it is about six inches above her. Also, when the victim is talking to Andy she says that she felt the tip of the knife, that he was about to drive it into her, but he was stopped by three woman. (00:24:15)
Continuity mistake: Episode 8x17, "Generation Hex": When Phoebe hands Paige her wedding gift, the way Paige holds it changes between shots. (00:01:20)
Something Wicca This Way Comes - S1-E1
Continuity mistake: At the beginning of the episode they show Piper running up the stairs to her house in the rain. The umbrella she has is black, with a colored ring around the edge. When she enters the house the whole umbrella has changed to colors surrounding the whole umbrella now. (00:02:35)
Continuity mistake: When the banshee came to the attic, she smashed all of the windows, except for some in the middle of the big window, but in the next shot that glass was gone.
Gone With The Witches - S8-E20
Continuity mistake: When the leprechauns are called back to the manor from Magic School, O'Brien cradles his injured arm in his left hand. In the next shot, his arm is down by his side and he moves it to his arm again. (00:25:10)
Continuity mistake: When Prue leaves Buckland's, she's wearing a red tank top, but when she arrives at Camp Skylark, her shirt is different, both in style and color. She can't have stopped to change, because it's mentioned she left the auction house and headed directly to the camp. (00:07:00 - 00:09:20)
Continuity mistake: In the scene where Cole has caught Phoebe's karate kick at school, Phoebe's hands are both clutching her school books. In the following shot, her left arm is in a completely different position, and there's no reason for her to have moved it. (00:18:25)
Continuity mistake: When Candor interrupts the Noxon demons torturing a student at Magic School, Rondok turns around to look at him. In the following shot, he's facing the other way and turns around again. (00:06:10)
Thank You for Not Morphing - S1-E3
Continuity mistake: When Prue tells Victor to leave the auction house, Victor has his arms behind his back, but in the next shot, his arms are in front of him. (00:09:40)
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.