We All Scream for Ice Cream - S3-E10
Visible crew/equipment: When Phoebe gets an IM on the laptop Prue walks over to her, and just as Prue sits down at the table we can see the blue tape mark on the floor, where she had been standing. (00:05:50)
We All Scream for Ice Cream - S3-E10
Continuity mistake: When the girls are saying goodbye to their father, Phoebe hugs him around the neck, then lowers her arms while they talk. When her father says "About anything," her left arm jumps back up to being around his neck, and in the next shot, it's down at the side again. (00:40:20)
We All Scream for Ice Cream - S3-E10
Continuity mistake: When Victor is saying goodbye to Prue, Piper, and Phoebe, Prue has her hands in her jeans pockets, then crossed in front of her, then back in her pockets. (00:40:45)
We All Scream for Ice Cream - S3-E10
Visible crew/equipment: When Prue and Phoebe are trying to pull the girl out of the ice-cream truck, in one brief shot, you can see the wires holding the girl up.
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.