1 Guide: If you'll just cross this bridge, we'll begin our tour of the space station.
2 Guide: {leads them out across an extremely narrow bridge} Just mind your step.
3 Guide: Does anyone have any questions?
4 Paris: {looking over the edge of the bridge} Why do space stations all have apparently bottomless chasms spanned by narrow bridges with no guard rails?

2011-12-24 Rerun commentary: Because there's No OSHA Compliance!

And... aha! There it is! The baseplate that I said earlier was perhaps the most used background element in Irregular Webcomic! That's it in the background, held vertically and with its underside exposed to the camera. It forms the random background wall seen in many, many strips. And on the other side of that wall are hills, a river, bushes, and palm trees growing horizontally.