!!!The Miniseries:
* CaliforniaDoubling: The Czechoslovakia scenes were filmed in and around Glasgow.
* CreatorPreferredAdaptation: Creator/JohnLeCarre was so impressed by Creator/AlecGuinness' performance as George Smiley that in later novels he wrote Smiley's characterization to be in keeping with Guinness's performance.
* PlayingAgainstType: This was a rare dramatic role for Beryl Reid, who was known for light comedy. Creator/AlecGuinness was initially opposed to her casting, but she won him over.
* TroubledProduction: The series was plagued by a series of strikes. Due to shooting overruns, a large number of actors moved to other projects without finishing their roles.

!!!The Film:
* ActorAllusion: It seems that Creator/JohnHurt [[Literature/NineteenEightyFour always had a lot of experience]] [[Film/VForVendetta with British political extremes and secret services]].
* AllStarCast
* AwesomeDearBoy: Creator/BenedictCumberbatch stated that playing a spy was his dream job - "you are NEVER what you seem."
* DawsonCasting: Karla's daughter is supposed to be in her twenties but the actress is in her thirties.
* DyeingForYourArt:
** Creator/GaryOldman's hair (lighter) and waistline (heavier).
** Creator/BenedictCumberbatch as well - Guillam's hair is blonde, while Mr. Cumberbatch is naturally a ginger.
* InMemoriam: The film is dedicated to screenwriter Bridget O'Connor, who completed work on the film before her passing away from cancer.
* PlayingAgainstType: Creator/ColinFirth and Creator/MarkStrong co-star in a movie where one plays a kindly schoolteacher haunted by his past, and one plays a depraved turncoat spy selling international secrets to the Soviets. [[spoiler: Sounds pretty typical, unless you know that Strong's the schoolteacher and Firth's the evil spy]].
* WhatCouldHaveBeen:
** ''Film/{{Oldboy|2003}}'' director Creator/ParkChanWook was offered the film at one point.
** Creator/MichaelFassbender was originally cast as Ricki Tarr, but he had to back out because he was busy filming ''Film/XMenFirstClass''.
** Creator/DavidThewlis and Creator/RalphFiennes were considered for roles.