The Good, the Bad and the Cursed - S3-E14
Continuity mistake: When Cole and Prue are about to shimmer to the other plain to find BO, Cole's face has not been shaved. But when they reach the other plain, his face is cleanshaven.
The Good, the Bad and the Cursed - S3-E14
Continuity mistake: After Cole kills the outlaw with an energy ball, he turns around to face Prue. In the following shot, he's facing the other way and turns around again. (00:39:45)
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.