Elizabeth Whitson appears in the Halloween episode as a character named Leah, who is appearantly Luke's cousin. However, when this episode was shot Whitson was still going to play Olivia, Luke's twin sister, in the actual spin-off show. The role was recast with Merrit Patterson after this episode was shot and before the first episode for Ravenswood was shot. If you look closely you can see the dialogue was changed during post-production and doesn't match up with what her lips are saying. Her lips are saying 'No, that was my brother', but we're hearing 'cousin' instead of 'brother'. When Luke calls her 'Leah', that's also off-screen. He was probably calling her 'Olivia' before.