The game's original full title was Bioshock 2: Sea of Dreams.
There is an unused video in the game's files called "gul_sinc_dies.bik" The video is low quality, silent and looping, implying it was originally meant to played on a monitor in-game. The video shows Sinclair bound to a chair, the title implies he dies soon after. Spoiler:In the final game, Sinclair is transformed into an Alpha Series Big Daddy and dies by your hand. The title also uses the prefix "gul". Oddly, the only other videos with the "gul" prefix are the cutscenes used for the end of the game.
A frozen cat named SchrÃ¶dinger can be found in Imago Fine Arts at the Dionysus Park level. This is a reference to the famous thought experiment SchrÃ¶dinger's Cat.