- "...after falling down some stairs" (next comic, George reaching "from our world" conclusion)
The obvious nitpick here is "but they already went up the stairs!"
Firstly, I suspect there's more danger of falling when going downstairs than up, as people are more prone to falling forward. Falling while going up the stairs could still go very badly, of course, but as far as I'm aware, there's more opportunity to recover safely.
Secondly, the way Ellen narrated things, they effectively teleported there. That's not what happened in-game, but the opportunity was not given for an "oh no, stairs" moment.
Not that I'm arguing one was needed. I'm just addressing why there wasn't this sort of moment earlier.