The final "Graduation" episode had already been shot when the network ordered additional episodes. Tiffani Thiessen and Elizabeth Berkley were attached to other projects by that time, necessitating the creation of a replacement character Tori, played by Leanna Creel. The Tori episodes aired in the middle of the other final season episodes to sidestep continuity problems (though the disappearance and later reappearance of Kelly and Jessie, as well as for Tori, went unexplained). - and vise versa for Tori- went unexplained).