* BillingDisplacement: Creator/JanetLeigh over Creator/AngelaLansbury, who plays a much more important role.
* CompletelyDifferentTitle: The French title of this movie is ''Un Crime dans la Tête'', which can be translated as ''A Crime in the Head'' or ''A Crime in Mind''.
* CreatorChosenCasting: Creator/JohnFrankenheimer insisted on casting Creator/AngelaLansbury, having worked with her on ''All Fall Down''.
* DeniedParody: Creator/MerylStreep denied that her character in the remake was a parody of UsefulNotes/HillaryClinton. Given that [[OlderThanTheyThink the original version of the film was released in the 1960s and its source novel in 1959]], she probably has a point. (Although, they ''do'' have similar PowerHair...)
* FakeAmerican: Creator/AngelaLansbury and Creator/LaurenceHarvey, who are both British.
* FakeNationality: American Creator/HenrySilva and Khigh Dhiegh as the Korean Chun-Jin and the Chinese Dr. Yen Lo, respectively.
* {{Joisey}}: In the hotel scene, the soldiers have been brainwashed by Dr. Yen Lo to believe they are waiting out a storm in New Jersey (which the placard for the "flower club" reads as Spring Lake Hotel), while they are actually being displayed to demonstrate the effectiveness of the brainwashing to an audience of Communist officials. [[FakeNationality American actor Khigh Dhiegh who plays Dr. Lo was born in Spring Lake, New Jersey.]]
* KeepCirculatingTheTapes: The original film was rarely available in the years in between its initial 1962 release and its 1988 reissue. This has led to rumors that Music/FrankSinatra had the film pulled from distribution after [[HarsherInHindsight the Kennedy assassination]]. In reality, the film's shelving had more to do with studio politics than regular politics. When the film bombed at the box office, United Artists reneged on a deal that kept Sinatra out of any royalties. When the rights reverted to Sinatra in 1972, his lawyers, angry that their client was screwed over, had the film suppressed and pretended it never existed. The only explanation as to why the film was re-released was because Sinatra had new lawyers.
* NoStuntDouble: In an interview with ''Starlog'' Magazine in 1990, Creator/HenrySilva said "no one was doubled" in the fight scene between him and Creator/FrankSinatra.
* OnSetInjury: Creator/FrankSinatra injured his hand during the filming of his fight scene with Creator/HenrySilva. Accounts vary as to whether it was a broken finger (according to Music/NancySinatra) or a broken wrist (according to other sources), but all agree that he carried on filming through the injury and it never healed properly as a result.
* PlayingAgainstType:
** It wasn't playing against type at the time, as Creator/AngelaLansbury had played her fair share of schemers and antagonists. But for a modern-day viewer who might know her from ''Series/MurderSheWrote'' or Disney's ''WesternAnimation/BeautyAndTheBeast'' and ''Film/BedknobsAndBroomsticks'' (the latter of which came out less than a decade after ''The Manchurian Candidate''), watching her play Mrs. Iselin could be jarring given how ruthless and un-motherly Iselin is compared to characters like Mrs. Potts.
** This is sometimes seen as applying to Frank Sinatra in this film, including on the trope's [[https://tvtropes.org/pmwiki/pmwiki.php/Main/PlayingAgainstType main page.]] However, it should be noted that by this point in his career, he had already established himself as not only a singer but a serious actor in critically acclaimed projects like [[https://tvtropes.org/pmwiki/pmwiki.php/Film/TheManWithTheGoldenArm The Man With the Golden Arm]] and [[https://tvtropes.org/pmwiki/pmwiki.php/Literature/FromHereToEternity From Here to Eternity]] - the latter which won him a Best Supporting Actor Oscar. So, while technically true, it wouldn't have been seen as THAT much of a departure at the time.
** Lloyd Corrigan as Holborn Gaines. Corrigan was a character actor regularly typecast as bunglers and doddering old fools subject to constant slapstick - usually in B-Westerns and family friendly sitcoms. And while Holborn Gaines is certainly an effeminate character (getting murdered in bed while wearing his dead wife's frilly bed jacket), it's mostly played straight and then in a much darker, more political context. Before the audience even officially sees Gaines, he's already been labelled a communist by a furious Mrs. Iselin (the first such character in the film to be the object of her incessant red-baiting).
* RealLifeRelative:
** When Major Bennett Marco is shown a photo of the Communist official Gomel at a child's birthday party, the two children in the photo are the children of writer and producer George Axelrod.
** The 2004 film co-stars Creator/PabloSchreiber, half-brother of star Creator/LievSchreiber.
* ThrowItIn:
** The scene where Marco tries to break Raymond's brainwashing using a deck of cards comprised totally of Queens of Diamonds is out of focus. Creator/FrankSinatra didn't quite match the intensity of his first performance in subsequent takes, so they used the blurry one. It kind of works to represent Raymond's disorientation.
** The fight scene where Ben punches his hand through a table is actually Sinatra accidentally punching his hand through a freakin' table and breaking a finger. The injury didn't heal properly and bothered him for the rest of his life.
** Creator/JohnFrankenheimer notes on the DVDCommentary that the scene where Senator Iselin argues with the Secretary of Defense was entirely ad-libbed.
* UncreditedRole: Creator/ReggieNalder is uncredited for his part as Gomel.
* UnderageCasting: Creator/AngelaLansbury was only three years older than Creator/LaurenceHarvey who played her son.
* WhatCouldHaveBeen: Sinatra originally wanted Creator/LucilleBall to play Mrs. Iselin, until Creator/JohnFrankenheimer suggested Creator/AngelaLansbury (whom he'd directed in his previous film, ''All Fall Down'') instead.
----