Near the end of the episode the Grimlocks are vanquished. When Darryl comes down the stairs Leo uses his Whitelighter powers to restore his sight. In an earlier episode that featured Grimlocks, anyone who was blinded by the Grimlocks had their eyesight restored automatically when the Grimlocks were destroyed.
When the Grimlocks are watching Darryl and Leo through the keyhole, one of them says that they have to wait until they are in their range. In Out of Sight (1999) they kill a man from a further distance than Darryl and Leo are.
Towards the end right after Darryl sends the kids away, the camera pans to living room and shows the unbroken coffee table. It was broken at the beginning of the episode when Prue threw one of the grimlocks. Then when the Grimlocks throw Darryl the coffee table is already broken again.
When Phoebe is sweeping the broom outside Ruth's house, she sweeps it left to right, but the long shot of the broom shows it moving right to left.
As one of the first episodes produced for the season this Halloween episode was filmed in the summertime, as evidenced by all of the green leafy trees seen, without any trees having the expected autumn colors or bare tree limbs one would see in late October.