- 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 five children; four biologically with Tennant also legally adopting Ty Tennant, who Georgia had from a previous relationship.
- Cast the Runner-Up: Georgia Moffet previously auditioned for Rose Tyler.
- Pop Culture Urban Legends: A fan myth concerning this episode states that incoming showrunner Steven Moffat learnt that Jenny was to be killed off at the end of the episode, and specifically requested that current showrunner Russell T Davies have her survive as he intended to use the character in the future. This is a result of Gossip Evolution: what actually happened was that Moffat made an offhand remark after reading the script that Davies had a habit of creating interesting characters then killing them off, and that prompted Davies to change his mind and have her come back to life at the end of the episode. When Moffat saw the episode go out, he was very surprised to find that Jenny now survived the episode, and was even more surprised to learn that he was the reason she did.
- 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"