- Cast Incest: Peter Davison, who played the Fifth Doctor (and who is pretty much the reason David Tennant went into acting), is Georgia Moffett's father. She is also now married to David Tennant. And they have three children.
- Romance on the Set: David Tennant met wife Georgia Moffett on the set of this episode.
- Throw It In!: Georgia Moffett had no plans to start crying during Jenny's death scene — those tears were inspired entirely by David Tennant's performance.
- What Could Have Been:
- The Doctor threatening to shoot Cobb was a late change. Originally, he was taken away to be executed.
- The Hath's opponents were originally called the Takrans, but this was excised because of its ambiguous pronunciation.
- The original plan for the story was to keep Jenny killed off. However, Steven Moffat noted that Russell T Davies seemed to have a habit of introducing interesting new characters and then promptly killing them off, which led Davies to change his mind.
- Word of God: According to Steven Moffat, Jenny did not regenerate but was brought back to life by the Source.
Trivia / Doctor Who S30 E6 "The Doctor's Daughter"