Alec Baldwin bowed out of this film when production was pushed back from '91 to '92. He had already committed to doing a revival of "A Streetcar Named Desire" on Broadway and told then Paramount President Brandon Tartikof to either work around him or find someone else to play Ryan. Ford was then approached to play Ryan in "Patriot Games" after having turned down the role in "The Hunt for Red October", because he felt the script was more focused on Captain Ramius than on Jack Ryan.
James Horner (who, like all composers, often re-uses his own material) borrows part of his score from Aliens (1986) in scoring this film. Specifically, the key elements of "Resolution and Hyperspace" from the "Aliens" soundtrack appears in this movie as the music that plays while Ryan and the others watch the SAS attack on the Libyan training camp.
Near the beginning of the film as Ryan and his wife are kissing in their hotel bed, she reminds him that he is supposed to be working on his speech for the Royal Military Academy. Ryan replies that he will "wing it". The next day at the Academy, there is a very brief shot of Ryan's notebook as he is making his speech. The page is blank, indicating that he is, in fact, winging it.
Paramount yanked all their advertising out of Variety when one of the magazine's film critics, Joseph McBride, called the film "fascistic, blatantly anti-Irish... a right-wing cartoon". Variety's editor Peter Bart privately sided with Paramount's boycott, calling McBride "unprofessional". Bart was subsequently embarrassed when his letter criticizing one of his reviewers and supporting studio censorship was leaked to the press. The Los Angeles Film Critics' Association and the National Society of Film Critics then publicly lambasted Bart for his "dismaying treatment" of one of his members of staff, saying "the question is not whether any responsible critic is right or wrong, but whether any responsible critic must be muted so as not to offend an advertiser or bruise a handful of tender egos".
The satellite attack-watching sequence features rather emotional, thinly scored music by James Horner, but the music is, in fact, taken quite directly from the slow movement of Dmitri Shostakovich's 5th Symphony. It's only for about half a minute that Horner does this, and he blends it into his own stuff, but that one little part is a very direct, uncredited grab.
Although this film was a sequel to The Hunt for Red October (1990), the action of the original novels was in the opposite order: the novel "Patriot Games" was a prequel. Presumably the change was made because Harrison Ford is older than Alec Baldwin.
The attack on members of the Royal Family at the very beginning of the film was inspired by a very similar true life attempt to kidnap Princess Anne on 20, Mar 1974. She was in her car when a man shot her guard and driver, then she was subsequently helped by a passerby who attacked the criminal and saved her.
In The Hunt for Red October (1990), during the initial briefing with the Joint Chiefs, doctor Ryan exclaims "son of a bitch!" after a moment of thoughtfulness - he does the same thing in this movie, during the discussion after he joins the Terror Assessment team. In addition, with a dash of subtle humor both scenes have someone saying "what?" after Ryan's exclamation. This "Ryan catchphrase" was abandoned in the subsequent Jack Ryan movies.
Jack Ryan refers to his wife as Catherine, when speaking to Lord Holmes but her first name in the novels is Caroline. This was probably to avoid confusion, because her nickname is "Cathy," which is usually a nickname to women named Catherine.
Early in the film, when Ryan gives a lecture at the Royal Naval Academy in London, he tells the audience, "In this volatile climate, we can only speculate on the future of Soviet Fleet development." In the foreground, a blueprint of the Soviet submarine "Red October" appears on a computer screen, establishing Ryan's link to The Hunt for Red October (1990).
When the IRA are coming to kill Kevin O'Donnell, he is watching the music video for Clannad's "Theme From Harry's Game" on his TV. This song was made for the TV series Harry's Game (1982), which is also about the Troubles, and some of the footage in the music video is taken from the series.
The cadence being sung at the beginning of the Annapolis scenes may be a common Marine Corp cadence ("Mission Top Secret, Destination Unknown"), but this cadence is derived from a common Army Airborne cadence ("C-130"). The reference to parachuting gives this away. All US Military personnel with parachute training go to the US Army Airborne School.
As Ryan is leaving the Annapolis academy, he crosses a street immediately in front of the main gate, which is signposted as "Hanover St." Harrison Ford and Hugh Fraser starred in the World War II drama, Hanover Street (1979).
The trivia items below may give away important plot points.
Tom Clancy objected to some of the changes made to his novel in the screenplay. In the novel, the noble that Ryan saves is in fact Prince Charles, and the tabloid reports of trouble in his marriage to Princess Diana is portrayed largely as the fabrication of a biased media. Subsequently, such reports would prove to be correct. The novel ends not with Miller's death, but with his capture by American authorities. He was captured originally in England, which has no death penalty, but finally captured in the United States, which does (and in Clancy's subsequent novel 'The Sum of All Fears', Miller and his fellow associates are executed by the State of Maryland for their crimes). Clancy felt that having him die in action robbed the story of this contrast.
In one scene where Jack Ryan is preparing breakfast for his daughter Sally, he asks her if she would like "...toast, or... toast?" Later on, in Clear and Present Danger (1994), Sally asks her younger brother this exact same question while she prepares him breakfast.
During the final scene in the kitchen, Jack opens the refrigerator door. On the door is a list of potential names for their next child. Under the heading of "Girls" are the names Samuel and Jackson. Samuel L. Jackson plays Robby in the film.
The original ending had Jack Ryan and Sean Miller fighting on large rocks in the middle of the stormy sea and Miller eventually drowning. Test audiences were not excited by this conclusion, so the new ending with the speedboat fight was filmed.