* BTeamSequel: 2k Marin took on the task of creating a direct sequel to ''VideoGame/{{Bioshock}}'' to free up Irrational to work on ''VideoGame/BioshockInfinite'', which, as it involved an entirely new setting, took much longer.
* {{Defictionalization}}: [=NECA=] has replicas of the EVE Hypo and Big Daddy dolls, just in case your normal Little Sister wasn't creepy enough. They also have one for the "bunny" and "wielder" Splicer masks.
* HeyItsThatVoice:
** The Little Sisters are voiced by Jodelle Ferland, who has experience playing a CreepyChild in films like Film/SilentHill.
* NamesTheSame: This game isn't [[{{Series/DoctorWho}} the only work]] to have character named [[Recap/DoctorWhoTVMTheTVMovie Dr. Grace Holloway]].
* PlayerPunch: [[spoiler:Having to MercyKill Sinclair as he's been captured and morphed into an Alpaha Series.]]
* ThrowItIn: "[[ViralMarketing Something In The Sea]]" wasn't going to have an effect on the main game, but fans loved it so much that protagonist Mark Meltzer was given a minor role.
* 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 there 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 use plasmids.
** Dionysus Park was originally conceived as being as a perfectly intact area that wasn't leaking and falling apart like the rest of Rapture. The player was originally supposed to get there by way of an underwater section through a completely flooded [[NostalgiaLevel Fort Frolic]].