Plot hole: In the episode where Jessica went home to her family's house in season 2, Bill said "someone who lives here must invite me in." In this episode, Russell Edgington's wolf (Coota) invites Russell into Alcide's apartment. Also, in Season 6 Sarah Newlin recinds Jessica's invitation into Jason's house (which only Jason should be able to do).
And Those We Left Behind - S4-E6
Plot hole: The very ending scene where Peter (in this version died in the ice as a boy so Walter's wife never met him) takes off some of the dust covers then picks up a toy airplane. The toy airplane he got as a child from ... Walter's wife when she was trying to placate him in an earlier episode for trying to run "home". This toy airplane wouldn't have been his as a child in this version of the universe. (00:42:00)