- Actor-Inspired Element/Written by Cast Member: The cuckoo clock speech wasn't in the original script. It was suggested by Orson Welles, inspired by a Hungarian play.
- The scene showing the waning moments of Harry Lime's life in which he extends his fingers futilely towards freedom through a grate in the sewer was suggested by Welles. The hands actually used in that shot belong to Carol Reed.
- AFI's 100 Years... Series:
- BFI Top 100 British Films: #1.
- Bad Export for You: Because of differing cultural tastes and content standards, the original American release trimmed 11 minutes from the British version. Carol Reed's Opening Narration was replaced with one by Joseph Cotten, Holly's scenes were edited to change him from an Anti-Hero into The Hero, and some content that would run afoul of The Hays Code was taken out (most memorably a scene with a dancer who was topless except for pasties). The British release is now the one in general circulation.
- Big Name Fan: Roger Ebert loved this movie, and included in his Great Movies Essays. He later said it was one of the 10 greatest films ever made.
- Billing Displacement: The video edition has Orson Welles alone on the cover, even though Welles only features in the last 20 minutes or so, and his appearance is supposed to be a reveal. Joseph Cotten is the actual star, although he does get top billing.
- Cast the Expert: The Vienna Police Dept. has a special unit that is assigned solely to patrol the city's intricate sewer system, as its network of interlocking tunnels make great hiding places for criminals on the run from the law, stolen property, drugs, etc. The "actors" playing police officers in the film were actually off-duty members of that unit.
- Cast the Runner-Up: Trevor Howard was briefly considered for Harry Lime before being cast as Major Calloway.
- Creative Differences: During the shooting of the film, the final scene was the subject of a dispute between Graham Greene, who wanted the happy ending of the novella, and Carol Reed and David O. Selznick, who stubbornly refused to end the film on what they felt was an artificially happy note. Greene later wrote: "One of the very few major disputes between Carol Reed and myself concerned the ending, and he has been proved triumphantly right."
- Ensemble Dark Horse: Despite only appearing in the latter third of the movie, Harry Lime became such a popular character that a prequel Radio Drama series with Lime as the protagonist (played again by Welles) was produced in 1951-52.
- Executive Meddling: David O. Selznick tried to micromanage the film from Hollywood, greatly annoying the British creative team. Selznick's main issue was the portrayal of Holly Martins as an Anti-Hero. He lost that battle, but succeeded at softening the character in the edits for the original American release.
- International Coproduction: This was a British movie largely filmed in Austria with David O. Selznick as an uncredited American co-producer.
- One for the Money; One for the Art: Orson Welles took the role as Harry Lime in order to fund his film adaptation of Othello. Also crosses over into What Might Have Been, in that Welles was offered either a straight paycheck or a third of the film's gross. He took the paycheck (being desperate for cash), but considering how huge a hit the movie was, had he taken the percentage, he might never have had to do paycheck work again.
- One-Hit Wonder: "The Third Man Theme" was Anton Karas' only hit. A full soundtrack album was ready for release when the film premiered, but wasn't released at the time due to lack of interest. While the film brought Karas a lot of attention, he wasn't really interested in being a performing star and eventually retired from the limelight.
- Reality Subtext:
- Graham Greene used to work for British Intelligence in WW2, where his boss and friend was the Double Agent Kim Philby. It's been speculated that Lime (a charismatic yet amoral friend secretly working for Soviet Intelligence) reflected underlying suspicions Graham had of Philby. In a particular irony, after Guy Burgess and Donald Maclean fled to Moscow to escape arrest, Philby fell under suspicion of being "the third man" in their spy ring.
- Post-war Vienna is almost a character itself. Carol Reed stated that the fact it was still being tussled over by the US, Brits and USSR gave it an air of tenseness it normally wouldn't.
- The Red Stapler: In Vienna there are canal tours called "Der Dritte Man -Tour" which visit the exact places where the scenes of Harry Lime being chased by the police were shot.
- Self-Adaptation: Graham Greene adapted his own novel. It was his only original screenplay.
- Throw It In!: The hotel manager points in the wrong directions when talking about Heaven and Hell due to the actor's trouble speaking English, which Reed loved as a symbol of post-war Vienna's skewed morality.
- What Could Have Been:
- This was intended to be the first of four films co-produced by Alexander Korda and David O. Selznick, but the two constantly clashed and never worked together again.
- Carol Reed originally wanted Cary Grant and Noël Coward for Holly Martins and Harry Lime, as in the novel both characters are English. Reed's second choice was James Stewart. Selznick suggested Robert Mitchum, but the actor's arrest for marijuana possession made that impossible.
- The original script included a return appearance by Basil Radford and Naunton Wayne, playing Captain Carter and Captain Tombs respectively, similar to Charters and Caldicott, the two English cricket enthusiasts who first appeared in The Lady Vanishes, and later in Carol Reed's Night Train to Munich (1940). However, the two characters were streamlined into the role of Mr. Crabbin, played by Wilfrid Hyde-White.
- Write Who You Know: Graham Greene based Harry Lime on British double agent Kim Philby, who was Greene's superior in the British Secret Intelligence Service.
Trivia / The Third Man