Originally Posted by BH/HHH
They were definitely skulls, my two options I think are dream or ai sequence after all the Kryptonians have died OR the dead inmates of Black Zero
Interesting and good guesses. I'm gonna theorize that it's like a 'spirit world' like phantom zone inside the Black Zero where Krypton's prisoners are subjected too and contained in. After Zod speaks to Kal aboard his ship (with Lois and Faora there) he roughs him up (him dropping to his knees and throwing up blood) and then puts him in this containment skeleton prison hell vortex (where he's reaching out for Lois).