- Shrug of God: The gender of Sam, and consequently whether Sam's relationship with Archie is straight or gay. Scalzi deliberately used a unisex name and avoided using any gendered pronouns to refer to the character, and says he doesn't know himself.
- Throw It In!: Scalzi didn't initially intend the above, but when he realized he'd managed to go several pages without making clear the gender of someone with a unisex name, he decided to keep it up through the whole book.
Trivia / The Android's Dream