Proverbial Jon said:
One of the commentary nodes talks about how Valve had to try and put all the different sections of the game together, how they had to make sure that you got to each area in a way that was believable. It ends by asking the player if they can spot the one transition which was completely implausible. I'd say that was the long elevator ride at the ending. Just a guess.
Actually, there's no evidence that there weren't loads of facility between you and the surface, and they've all just fallen away because Wheatley was doing such an incompetent job at taking care of the place.
On the other hand, my opinion for the implausibility is the moon itself. Think about it. When you're hanging out in space, desperately holding on, you tilt your head up... and see the Earth. Think about the angles - the Earth should be directly behind you, enough so that she should see it when she gets hit by the space-sphere and she turns around, not just by looking over the horizon. I think that's what he was referring to because while I can at least attempt to handwave the close-to-the-surface thing, I really have no idea how to handwave
this...