Entertainment Weekly reported that Meryl Streep watched political talk shows to prepare for her role: "anything with Peggy Noonan, Karen Hughes... it's hard to get more hyperbolic than that." She didn't watch the original film until after filming wrapped.
When Raymond Shaw is talking with Ben in his election HQ office, he says, "...when we were in Kuwait..." but slurs the word to sound very much like "Korea". The original movie had the soldiers serving in (and abducted from) Korea.
When Shaw's Secret Service agent plants the rifle at the rally site for Marco, the spoken word piece "Kinky Sex Makes the World Go Round" by Dead Kennedys can be heard. The piece is about the U.S. "Secretary of War" calling Britain's Prime Minister suggesting "it's time to start another war", and suggesting that both countries give their soldiers, and young people who might be drafted, drugs to ensure compliance.
Before this movie's release, Paramount set up two official websites: one site with movie information, and one site that appeared to be a promotional tool for the (fictional) Manchurian Global Corporation depicted in the movie. The corporation website gave no indication of its connection to the movie except a few references to its sponsorship of Dr. Atticus Noyle's Alzheimer's research. Similar advertisements for fictional medical procedures and clinics were also produced as parts of the advertising campaigns for Gattaca (1997), Godsend (2004), and Eternal Sunshine of the Spotless Mind (2004). Besides these films listed, Resident Evil: Apocalypse (2004) also has a advertising campaign featuring "Regenerator", a fictional product developed by the Umbrella Corporation.
The radio chatter audio near the end of the film as Ben returns to the beach is actually a recording of a Norfolk Southern train defect detector. If one listens carefully you can even hear it state, "NS (Norfolk Southern) detector milepost 79.8 one no defect." The actual detector likely reported 79.8 track one but the word track would spoil the illusion. It is interesting because these automatic reports only transmit two or three miles to inform the train crew of defects in their train. It is not likely they would be heard on a remote island.
There is a brief shot of Worldwide Plaza (49th-50th Streets & 8th Ave, NYC), the office complex on the site of the second (1925-1966) Madison Square Garden, where, in the original The Manchurian Candidate (1962), the assassination takes place (the inside and outside of the old Garden are shown in the original movie).
In Richard Condon's novel The Manchurian Candidate, the relationship between Mrs. Iselin and her son Raymond is more explicitly incestuous, complete with a bed scene. For the 1962 adaptation, director John Frankenheimer and screenwriter George Axelrod wanted to include that element, but reduced it to the less-than-motherly kiss that Mrs. Iselin plants on Raymond's lips. To appease the censors, Frankenheimer instructed Angela Lansbury to put her hand between their mouths and the camera during the kiss to obscure what she was doing a bit. By time of Jonathan Demme's 2004 remake, the incestuous content between the mother and son shown on screen had been reduced even more, so that the camera cuts away before she kisses her son on the lips, only leaving the implication of that relationship between them.