- No Stunt Double: Karen Gillan was allowed to perform several of her own stunts in the episode. She was excited to learn that her character would fight pirates with swords, and was taught how to handle one with basic moves. Gillan was also allowed to swing across the ship. However, a stunt double was required to film the sequence where Amy is thrown across the deck by the Siren.
- Recycled Script: The episode uses almost exactly the same Twist Ending as "The Empty Child"/"The Doctor Dances", revealing that the Monster of the Week was actually just medical software for an abandoned alien ship, and that its actions were the result of it blindly following its programming and trying to heal injured humans without understanding human physiology. The plot even involves a young boy's relationship with a distant parent that he barely knows. It takes place in The Golden Age of Piracy instead of World War II, and the monster is a siren instead of a zombie, but the plots are otherwise exactly the same.
- What Could Have Been: One late deletion from the script was the idea that the Siren would appear to Toby Avery as a young girl. This would have given the Doctor a clue as to the entity's true nature.
- Working Title: The Siren.
Trivia / Doctor Who S32 E3 "The Curse of the Black Spot"