butterfly | Madama Butterfly | Arvo Pärt | Butterfly | Iron Butterfly | Doppler effect | Swallowtail butterfly | Mass Effect | Harry Potter and the Deathly Hallows – Part 1 | The Godfather Part II | Friday the 13th Part III | Special effect | Monarch butterfly | M. Butterfly | Mass Effect 3 | Magnus effect | Venturi effect | Mössbauer effect | Henry VI, Part 2 | Henry IV, Part 1 | Harry Potter and the Deathly Hallows – Part 2 | Hall effect | Butterfly stroke | The Twilight Saga: Breaking Dawn – Part 1 | The Decline of Western Civilization Part II: The Metal Years | Rambo: First Blood Part II | Till Death Us Do Part | Swimming at the 2013 World Aquatics Championships – Men's 50 metre butterfly | sound effect | Part 2 |
The episode also sees the return of former guest star Kristen Johnston (Helen) who was last seen in "The Butterfly Effect Part 2".