Obviously, this is all spoiler territory from here on out.
The ending finds Gabriella Wilde’s Sue Snell in the hospital, very much pregnant and about to give birth. The minute-and-a-half alternate scene drags on, depicting a painful baby deliver until…well, just watch. It’s got a Humanoids from the Deep vibe.
I kind of prefer this one to the theatrical ending. It’s just batshit crazy enough for me.