Be Careful What You Witch For - S2-E22
Plot hole: When teenage Prue has run away with the demon, and Phoebe and Piper find her in the park, teenage Prue is 'killed'. Her sisters drive her home to get Leo to heal her, but shouldn't they have just been able to call to Leo to orb to them when Prue was first hurt, and heal her in the park, and save driving back to the Manor, risking Prue dying?
Suggested correction: I see orbing to the park but he didn't heal her, she was already dead and he can't heal the dead, that's why the genie brought her back - that's what Phoebe wished for.
But if they would have called for him right away - he would have been able to heal her before she died. However at this point in time I don't think they knew how to call for him.
Coming Home - S4-E1
Visible crew/equipment: In the scene where Joey and Pacey have arrived back at Capeside, and are getting things ready to get off the "True Love," in one shot you can see the microphone clipped to the back of Joey's shorts.
Revealing mistake: When Rachel and Adam first meet, their cars crash in the car park. In the shot where they both get out of their cars, you can see a dry patch of ground under Rachel's car, but the rest of the area is wet. Why would that space be dry, if Rachel just crashed and it isn't raining heavily at the time?
Crystal Blue Persuasion - S3-E15
Factual error: When Frank, Olga and he rest of the Back Step Team meet Commander (a Navy O-5 Rank) William Streck, he is dressed in a U.S. Air Force Uniform with the rank of Colonel (O-6).
Plot hole: During the episode "Superstition", Onizuka thinks he has cancer because the magnetic pain-pads he was wearing created strange blobs in the X-Ray he has taken. However, given the fact that the X-Ray was so strange, doctors would have given him a complete physical, and noticed the pads much sooner. Here, they literally just assume he has tumors, and fail to ever take notice of the pads. Simply impossible, given the gravity of the situation. (Obviously, this is to pay off at the very end of the episode.)