to be added
- The Structure is located on an unknown planet in E-Space with two suns.
- Adric worries that the two Time Lords, with life spans of centuries, would think nothing of spending months in one place.
- The stories in Short Trips: Steel Skies are divided into four sections dealing with different types of confinement. This story deals with isolation, that is, "the loneliness and despair of being cut off from the world outside".