After Dr. Wolf puts the stick through Sheila's neck, there is no mark on her neck where the stick went through. As seen in other scenes, it is possible for Sheila to have cuts and wounds on her body.
Joel tells Dr. Wolf that Principal Novak's grandmother told him both her parents were Serbian, explained how they died, and made him touch locks of their hair, all on a long afternoon. However, he had only met her one time at this point and it appears the entire brief encounter was shown, and none of this occurred.