History Trivia / DoctorWho2015CSTheHusbandsOfRiverSong

* WhatCouldHaveBeen: Much like Creator/JennaColeman last season, Creator/StevenMoffat intended for a while to have this be his last episode before passing the show to a new runner, hence his using it to finally tie off his very first original plot thread. At some point before production, however, he decided, or was asked, to stay on for one more season.

* AuthorsSavingThrow: After River's story seemed to end two series ago without any explanation of the Singing Towers of Darilium, one of the few specific references she ever made to the exploits in her past and the Doctor's future, it's finally revealed here. (Actually, it ''had'' been revealed, in a made-for-DVD mini-episode titled "Last Night", but many fans never saw or were resentful that a major moment was blown off as a DVD extra.) Also, her having pictures of all the Doctor's incarnations removes the plot hole that she wouldn't immediately realize she'd reached the point where the Doctor had never met her before during her fateful adventure with the Tenth Doctor, when apparently her entire relationship had been with the Eleventh. Her mentioning having "borrowed" the TARDIS in the past could also mean she had met or at least seen previous incarnations -- a conceit promptly picked up by the ExpandedUniverse Creator/BigFinish audio dramas (which patches ''another'' hole left by River's whole relationship apparently being with Eleven - before we knew her history, it sure ''seemed'' like she'd known the Doctor through many incarnations.)

* CastingGag: The prodigiously tall (6ft 8in) Greg Davies plays Hydroflax... and spends almost the entire episode as a disembodied head.
* ContinuitySnarl: This episode retcons an earlier made-for-DVD mini-episode titled "Last Night" in which the ''Eleventh'' Doctor was depicted as the incarnation that took River Song to Darillium before sending her off to meet her fate at The Library. As a result, it causes issues with many major plot points in episodes from "[[Recap/DoctorWho2012CSTheSnowmen The Snowmen]]" through to "[[Recap/DoctorWhoS35E12HellBent Hell Bent]]", with the most major arguably being that of "[[Recap/DoctorWho2013CSTheTimeOfTheDoctor The Time of the Doctor]]" in which the Eleventh Doctor spends nearly a century on Trenzalore living out what he believed to be his final incarnation and fully expecting to die; it is only because of unexpected interference from Clara Oswald that this does not occur. Had he died, a universe-destroying paradox would have occurred as he would not have resolved River Song's timeline. What might be dismissed as a continuity error is amplified when one recalls that such paradoxes were major plot elements of [[Recap/DoctorWhoS35E4BeforeTheFlood two key]] [[Recap/DoctorWhoS35E12HellBent episodes]] of the season that had concluded just three weeks prior to this special being broadcast. See the "Headscratchers" section of this episode's listing for examples of how fans are trying to reconcile this.

* WhatCouldHaveBeen: Much like Jenna Coleman last season, Steven Moffat intended for a while to have this be his last episode before passing the show to a new runner, hence his using it to finally tie off his very first original plot thread. At some point before production, however, he decided, or was asked, to stay on for one more season.

* WhatCouldHaveBeen: Much like Jenna Coleman last season, Steven Moffat intended for a while to have this be his last episode before passing the show to a new runner, hence his using it to finally tie off his very first original plot thread. At some point before production, however, he decided to stay on for one more season.

* HeyItsThatGuy: Nardole is [[Series/LittleBritain Matt Lucas]] and King Hydroflax is [[Series/MockTheWeek Greg]] [[Series/WouldILieToYou Davies]]--both comedians who are [[BlackComedy not exactly known]] [[ToiletHumor for being PG rating-friendly]].
* HeyItsThatVoice: The voice of Hydroflax's body is [[Series/GameOfThrones Nonso]] [[Series/{{Dracula}} Anozie]].

* WhatCouldHaveBeen: Much like Jenna Coleman last season, Steven Moffat intended for a while to have this be his last episode before passing the show to a new runner, hence his using it to finally tie off his very first original plot thread. Then he decided at the last minute to stay a while longer.

* WhatCouldHaveBeen: Much like Jenna Coleman last season, Stephen Moffat intended for a while to have this be his last episode before passing the show to a new runner, hence his using it to finally tie off his very first original plot thread. Then he decided at the last minute to stay a while longer.

* FandomNod: People ''do'' usually need flowcharts to figure out how exactly The Doctor's and River's timelines play out against each other.

* WhatCouldHaveBeen: Much like Jenna-Louise Coleman last season, Stephen Moffat intended for a while to have this be his last episode before passing the show to a new runner, hence his using it to finally tie off his very first original plot thread. Then he decided at the last minute to stay a while longer.

* WhatCouldHaveBeen: Much like Jenna Louise-Coleman last season, Stephen Moffat intended for a while to have this be his last episode before passing the show to a new runner, hence his using it to finally tie off his very first original plot thread. Then he decided at the last minute to stay a while longer.

* HeyItsThatVoice: The voice of Hydroflax's body is [[Series/GameOfThrones Nonso]] [[Series/{{Dracula}} Anozie]].

* HeyItsThatGuy: Nardole is [[Series/LittleBritain Matt Lucas]] and King Hydroflax is [[Series/MockTheWeek Greg]] [[Series/WouldILieToYou Davies]]--both comedians who are [[BlackComedy not exactly known]] [[ToiletHumor for being PG rating-friendly]].

* HeyItsThatGuy: Nardole is [[LittleBritain Matt Lucas]] and King Hydroflax is [[MockTheWeek Greg]] [[WouldILieToYou Davies]]--both comedians who are [[BlackComedy not exactly known]] [[ToiletHumor for being PG rating-friendly]].