History Trivia / DoctorWhoS10E1TheThreeDoctors

** Jamie was supposed to return and have a romance with Jo. Creator/FrazerHines was busy with ''Series/{{Emmerdale}}'' and his lines were given to Benton. To try and salvage the idea of Jamie appearing, they even tried to write a cameo for him in the last scene calling the Second Doctor back to his own timeline. Even that was scrubbed due to ''Emmerdale'' commitments.

* HostilityOnTheSet: Creator/TerranceDicks was once asked how Creator/PatrickTroughton and Creator/JonPertwee got on and he jokingly replied "Not at all". Initially, the two clashed over differing acting styles and working methods — Troughton was fond of ad-libbing and goofing around, while Pertwee insisted on sticking to the script.[[note]]A lot of this boiled down to cues -- Pertwee was a stickler for memorizing his lines and delivering them exactly, expecting his colleagues to do the same to provide him his cues. Troughton's much freer line delivery often threw him off balance.[[/note]] After Pertwee questioned Troughton on one of his ad-libs, Troughton replied, "Instead of worrying about what I'm going to say, worry about what you're going to say." The two also quarreled over Pertwee's habit of moving Stephen Thorne (Omega) slightly to get better camera angles for himself, something that Troughton objected to as he felt the camera was rightfully focusing on the monsters. The two eventually did become good friends and would play up a mock rivalry at conventions.

** The serial was originally scripted to end with the first mention of Metebelis Three (though originally scripted as Metebelis Four), as the Doctor was to invite Jo on a trip to see the planet. This would have originally set up the story arc that would weave all the way through the season to "The Green Death", and beyond to "Planet of the Spiders." Due to time constraints, the line was cut, and the first mention of the attempts to travel to the Blue Planet would be in the next story.

** This resulted in an odd situation where Hartnell's wife made a concerned call to the Doctor Who production office when she learned he'd accepted the role and was worried he'd taken on more than his health would let him handle. This was the impetus for the "Time Eddy" video inserts.

* RoleReprisal: Creator/WilliamHartnell and Creator/PatrickTroughton returned.
* ThrowItIn: Creator/NicholasCourtney's line about Cromer was improvised.

* HostilityOnTheSet: Creator/TerranceDicks was once asked how Creator/PatrickTroughton and Creator/JonPertwee got on and he jokingly replied "Not at all". Initially, the two clashed over differing acting styles and working methods — Troughton was fond of ad-libbing and goofing around, while Pertwee insisted on sticking to the script. After Pertwee questioned Troughton on one of his ad-libs, Troughton replied, "Instead of worrying about what I'm going to say, worry about what you're going to say." The two eventually did become good friends and would play up a mock rivalry at conventions.

** Jamie was supposed to return and have a romance with Jo. Creator/FrazerHines was busy with ''Series/{{Emmerdale}}'' and his lines were given to Benton.

** The First Doctor was supposed to meet Two & Three in person and be personally involved with their adventure in the antimatter world and the confrontation with Omega. However, because William Hartnell's arteriosclerosis was taking a serious toll on his health when he was called up for the serial, the script was re-written to trap One in a time eddy, with his lines being split between Two & Three. A similar workaround would later be devised when Creator/TomBaker rejected the chance to reprise the role of Four in [[Recap/DoctorWho20thASTheFiveDoctors "The Five Doctors"]].

* HostilityOnTheSet: Creator/TerranceDicks was once asked how Creator/PatrickTroughton and Creator/JonPertwee got on and he jokingly replied "Not at all". Initially, the two clashed over differing acting styles and working methods — Troughton was fond of ad-libbing and goofing around, while Pertwee insisted on sticking to the script. After Pertwee questioned Troughton on one of his ad-libs, Troughton replied, "Instead of worrying about what I'm going to say, worry about what you're going to say". The two eventually did become good friends and would play up a mock rivalry at conventions.

** The First Doctor was supposed to meet Two & Three in person and be personally involved with their adventure in the antimatter world and the confrontation with Omega. However, because William Hartnell's arteriosclerosis was taking a serious toll on his health when he was called up for the serial, the script was re-written to trap One in a time eddy, with his lines being split between Two & Three. A similar workaround would later be devised when Creator/TomBaker rejected the chance to reprise the role of Four in "The Five Doctors".

* RealitySubtext: Creator/WilliamHartnell was unable to take on a role in the story due to illness, hence he's trapped in a time eddy and only being able to communicate with his successors through a viewscreen in the TARDIS. On top of that, it wasn't just his last appearance as the First Doctor, but his last acting appearance ''ever''.

* MilestoneCelebration: The 1st multi-Doctor Adventure in honour of the 10th anniversary? ...yep, it's this trope in action! Though because it aired as the first story of the 10th season, and because the starting date of each season had shifted over the years, it actually aired only a month after the ''ninth'' anniversary.

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* HostilityOnTheSet: Creator/TerranceDicks was once asked how Creator/PatrickTroughton and Creator/JonPertwee got on and he jokingly replied "Not at all". Initially, the two clashed over differing acting styles and working methods - Troughton was fond of ad-libbing and goofing around, while Pertwee insisted on sticking to the script. After Pertwee questioned Troughton on one of his ad-libs, Troughton replied, "Instead of worrying about what I'm going to say, worry about what you're going to say". The two eventually did become good friends and would play up a mock rivalry at conventions.
* MilestoneCelebration: The 1st [=Multi-Doctor=] Adventure in honor of the 10th anniversary? ...yep, it's this trope in action! Though because it aired as the first story of the 10th season, and because the starting date of each season had shifted over the years, it actually aired only a month after the ''ninth'' anniversary.
* RealitySubtext: Creator/WilliamHartnell was unable to take on a role in the story due to illness, hence he's trapped in a time eddy and only being able to communicate with his successors through a viewscreen in the TARDIS. On top of that, it wasn't just his last appearance as the First Doctor but his last acting appearance ''ever''.
* ThrowItIn: Creator/NicholasCourtney's line about Cromer was improvised.

** In the original version, ''Deathworld'', the Time Lords are in conflict with a Federation of Evil led by a personification of Death. To avert all-out war, the Time Lords manage to convince the Federation to allow them to send the three Doctors into the Federation's Underworld domain. There, the Doctors will do battle against various realisations of Death -- including zombies, the Four Horsemen of the Apocalypse, the Hindu goddess Kali, and the cyclops Polyphemus from Greek mythology -- with the victor in the contests determining whether the Time Lords or the Federation of Evil will prevail.

** The First Doctor was supposed to meet Two & Three in person and be personally involved with their adventure in the antimatter world and the confrontation with Omega. However, because William Hartnell's arteriosclerosis was taking a serious toll on his health when he was called up for the serial, the script was re-written to trap One in a time eddy, with his lines being split between Two & Three. A similar workaround would later be devised when Creator/TomBaker rejected the chance to reprise the role of Four in ''The Five Doctors''.

* ThrowItIn: Nicholas Courtney's line about Cromer was improvised.

* YouLookFamiliar: The Chancellor of the Time Lords is played by Clyde Pollitt, who played one of the Time Lord judges who exiled the Doctor to Earth in "[[Recap/DoctorWhoS6E7TheWarGames The War Games]]". This was deliberate on the part of the production staff, in order to create a link back to "The War Games".

* MilestoneCelebration: The 1st [=Multi-Doctor=] Adventure in honor of the 10th anniversary? ...yep, it's this trope in action! Though somewhat subverted when one remembers that this is a year ''before'' the actual anniversary.

* MilestoneCelebration: The 1st [=Multi-Doctor=] Adventure in honor of the 10th anniversary? ...yep, it's this trope in action!

* TroubledProduction: As well as William Hartnell's poor health, Creator/PatrickTroughton and Creator/JonPertwee did not get on well during recording, as Troughton's tendency to improvise whenever he thought that he could improve on the script made Pertwee uncomfortable. This had knock-on effects ten years later during the making of "The Five Doctors", with Terrance Dicks deliberately writing the script so that the Second and Third Doctors would not meet until everybody came together at the climax, which ended up disappointing both Troughton and Pertwee, who had become more friendly in the intervening years through doing fan conventions.

** The First Doctor was supposed to meet Two & Three in person and be personally involved with their adventure in the antimatter world and the confrontation with Omega. However, because William Hartnell's arteriosclerosis was taking a serious toll on his health when he was called up for the serial, the script was re-written to trap One in a time eddy, with his lines being split between Two & Three.

* RealitySubtext: Creator/WilliamHartnell was unable to take on a role in the story due to illness, hence he's trapped in a time eddy and only being able to communicate with his successors through a viewscreen in the TARDIS. On top of that, it wasn't just his last appearance as the First Doctor but his last acting appearance ever.

* RealitySubtext: Creator/WilliamHartnell was unable to take on a role in the story due to illness, hence why he's trapped in a time eddy and only being able to communicate with his successors through a viewscreen in the TARDIS. On top of that, it wasn't just his last appearance as the First Doctor but his last acting appearance ever.

* WhatCouldHaveBeen: In the original version, Deathworld, the Time Lords are in conflict with a Federation of Evil led by a personification of Death. To avert all-out war, the Time Lords manage to convince the Federation to allow them to send the three Doctors into the Federation's Underworld domain. There, the Doctors will do battle against various realisations of Death -- including zombies, the Four Horsemen of the Apocalypse, the Hindu goddess Kali, and the cyclops Polyphemus from Greek mythology -- with the victor in the contests determining whether the Time Lords or the Federation of Evil will prevail.

* YouLookFamiliar: The Chancellor of the Time Lords is played by Clyde Pollitt, who played one of the Time Lord judges who exiled the Doctor to Earth in "[[Recap/DoctorWhoS6E7TheWarGames The War Games]]". This was deliberate on the part of the production staff, in order to create a link back to "The War Games".

** Jamie was supposed to return and have a romance with Jo. Creator/FrazerHines was busy with ''Series/Emmerdale'' and his lines were given to Benton.
** Zoe was considered to return, but Creator/JonPertwee felt that too many returning characters would be distracting.

* HarsherInHindsight: A somewhat tragic one, considering William Hartnell passed away between this and the 20th anniversary special, necessitating Richard Hurndall to be recast as the First Doctor.
--> '''The last line from the First Doctor:''' Though considering the way things have been going, well, I shudder to think what you'll do with out me.
** The BBC was also at the height of their wiping policy, and even episodes as late as Season 11's "Planet Of the Spiders" (Pertwee's final serial) were in danger of being wiped. The most recent recovery of a First Doctor episode? Galaxy 4 Episode 3 in 2011.

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* MilestoneCelebration: The 1st [=Multi-Doctor=] Adventure in honor of the 10th anniversary? ...yep, it's this trope in action!

** The BBC was also at the height of their wiping policy, and even episodes as late as Season 11's "Planet Of the Spiders" (Pertwee's final serial) were in danger of being wiped. The most recent recovery of a First Doctor episode? Galaxy 4 Episode 3 in 2011.