* HeyItsThatVoice:
** The Little Sisters are voiced by Jodelle Ferland, who has experience playing a CreepyChild in films like Film/SilentHill.
* WhatCouldHaveBeen: A DummiedOut idea for the plot would have involved [[DirtyCommunists Soviet soldiers]] invading Rapture. Part of the AI coding intended for the Russians eventually ended up being used by the splicers instead.
** A removed message from Eleanor revealed that Delta is her biological father (Sophia picked his DNA randomly from a bunch of archived DNA).
*** Originally their was only one Big Sister, Eleanor, who couldn't adjust to life on the surface and returned to Rapture. Furthermore, she would have been the one kidnapping children, and making them Little Sisters. However, this was removed as the game designers felt this twist was too predictable. You also would have played as the first Big Daddy, who as a result could think for himself, and could use plasmids as a result.