Plot hole: Throughout the series, it's established that good witches don't freeze. In this episode, however, Little Piper freezes Future Prue and Piper when they come back to the manor to "kidnap" their younger selves. Simply because the Charmed Ones reason that only one "set" of sisters (past/future) could have their powers doesn't mean that Future Prue, Piper and Phoebe aren't good witches. In other time-travel episodes, the sisters remain immune to freezing and are still able to say spells make potions, meaning they are still good witches. For example, in Season 8 "Forever Charmed," Piper and Leo go back to 1975 (the same time-period as this episode) using Coop's ring, trying to find when Phoebe is alive again. However, when a startled Patty tries to freeze them, only Leo freezes. Piper does not, though she likely cannot use her freezing/exploding power in this time.
Continuity mistake: In this episode, the sisters go back in time to late March 1975. On the family tree it says that Piper was born on August 7, 1973. So she would be 1 and 1/2 in March 1975. But she looks at least 2 years too old. (00:09:30)
Factual error: In the opening scene in Salem, Melinda Warren is going to be burned at the stake. But in the real Salem trials, no one was burned; all of the people convicted of witchcraft were hanged.
From Fear to Eternity - S1-E13
Plot hole: Prue finds an entry in the book of shadows about the fear demon written by her mother. How would her mother know anything about this demon when no one has seen him in nearly 1300 years, let alone how to defeat him?
Love Hurts - S1-E21
Continuity mistake: In this episode Leo specifically tells Prue, Piper and Phoebe not to touch the Darklighters arrow because it is poisonous however in future episodes/seasons, the Darklighter arrows are only poisonous to Whitelighters. (00:06:30)
Other mistake: When Andy, Phoebe and Prue are in the attic figuring out how to vanquish the ghost of Alcatraz, pages starts flipping, the book opens up to the page where the truth spell is, and Andy finds out that Prue cast that spell on him. Later when he asks how much time Prue gave him to react, she says "a minute or two". But in the episode "Truth is out there" (1-8) it was first in Prue's office when she told him, and the clock on the wall shows that it's 25 past 5. And it was 8 o'clock when Prue cast that spell. So few hours later when Andy and Prue are at Andy's door, it's almost 8 o'clock and Prue says she needs the answer now. So doesn't Andy have more like few hours rather than few minutes to react?
Wicca Envy - S1-E10
Audio problem: When talking about the tiara with a security guard Prue's mouth stops moving mid sentence but the audio continues.
Visible crew/equipment: When Piper is taken by Wong's men Mark shouts for help, and just as Prue tells Phoebe to call 911 from the car, the blue tape mark is visible on the rug beside the table, where the sisters had been standing before rushing out. (00:36:05)
Visible crew/equipment: When Prue is flicking through TV channels, just as Phoebe walks into the bedroom and stands beside her sister, we can see the movement of the camera operator and camera in the reflection within the standing mirror, near the door. (00:34:05)
Visible crew/equipment: After Piper takes the picture of Tony Wong holding the newspaper, when she and Mark quickly drive off, we can see the actors' large yellow T-mark taped to the ground near Wong and his men. (00:28:35)
Visible crew/equipment: When Aviva tells Phoebe that she wants to go upstairs because she's not feeling well, Aviva walks into the bedroom and just as she grabs her backpack part of the T-mark is visible on the floor where she stands. (00:33:45)
Wicca Envy - S1-E10
Visible crew/equipment: After Jaime tells Prue that she's the hardest working woman he's ever met and believes she's innocent, Prue walks into the office to access Hannah's computer, and just as Prue sits down and moves closer to the desk, the blue T-mark is visible on the floor, under the office chair. (00:24:30)
From Fear to Eternity - S1-E13
Visible crew/equipment: When Andy walks into the manor to speak with Prue, just as she tells him it must be bad news, we see the reflection of the boom mic on the glass door. (00:09:45)
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)
The Wendigo - S1-E12
Visible crew/equipment: When Phoebe joins her sisters in the kitchen before her first day at work, the reflection of the moving boom mic is visible on the glass cabinet, at the top of the screen. (00:10:05)
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)
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)
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)
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.