Plot hole: Piper mentions that Grams banished the Necromancer "sixty years ago" at Patty's Wiccanning. Grams soon thereafter says that the Necromancer has had "almost seventy years" to regain his strength. However, Patty was born in 1950, and this episode aired on 5/4/03, at which time Patty's Wiccanning could not have been more than 53 years earlier.
Deliberate mistake: In this episode Wyatt has his wiccaning. After all of the vanquishing is done with the Necromancer, it's finally time for the wiccaning and the spell that is said is this:"I call forth from space and time, Matriarchs from the Halliwell line, Mothers, daughters, sisters, friends Our family spirit without end, To gather now in this sacred place And help bring this child to grace." In this spell it is said to bring forth "daughters and sisters" from the Halliwell line, Prue died in the third season and this is now the fifth season, shouldn't she have been summoned as well to bring her nephew Wyatt to grace?