The shocker demon attacks because someone set the VCR to record, but the only reason the girls were aware of the VCR recording was because they heard the TV. The VCR recording wouldn't have made the TV turn on.
The prince is supposed to be frozen on Paige's living room couch, but in a close-up you can see the actor blink.
The point is made repeatedly, from the kitchen scene after the opening credits to the final scene, that the Halliwells can't use electricity for fear of allowing an attack by the Shocker Demon, but when Phoebe wants some water she takes it from the fridge.
When Phoebe suggests to Piper that the evil enchantress might be Paige's past life, Piper doesn't believe it with the reasoning that the evil enchantress' power is to summon the elements and Paige can't do that. The powers of the past life have nothing to do with the current life. Phoebe's past life had the power to throw fire and Phoebe can't, plus the girls current powers come from the charmed line.