There was some surprise that Stanley Baker, who, along with Sir Dirk Bogarde in 1960, was considered the most popular British movie star, accepted the relatively small supporting role of Private "Butcher" Brown. Baker revealed that he wanted to be in the movie because he was impressed at how anti-war the screenplay by the blacklisted writer Carl Foreman was.

This was the only time that David Niven ever smoked cigarettes on-screen. Niven was a life-long non-smoker.

Sir Anthony Quayle spent part of World War II in Albania organizing guerrilla forces. Like his character, Franklin, he was a Major.

During World War II, David Niven commanded units in the Commandos and the GHQ Liaison Regiment, a special reconnaissance unit that operated behind enemy lines.

Gregory Peck declined to attempt an English accent in order to play Captain Mallory.

David Niven initially felt that he was badly miscast in the offbeat role of a Corporal, but later said he considered it to be one of his best performances, despite being too old for the part.

William Holden was the first actor sought to play Mallory. He asked for seven hundred fifty thousand dollars, plus ten percent of the gross. He was turned down, and Gregory Peck was cast. Holden felt the role was too similar to the character he had played in The Bridge on the River Kwai (1957).

David Niven wears a Light Infantry cap badge on his beret. This was the regiment into which he was commissioned in World War II.

Although Navarone is a fictional place, the novel of the same title is based on The Battle of Leros, in the Dodecanese, the location of the deepest port in the region and coastal battery which defended it.

During shooting, Gregory Peck and David Niven became close friends, bonding initially over Peck's ability to consume vast quantities of brandy, which the actors used to "stay warm" while filming in a cold studio tank, without muffing a line. Their families visited each other frequently in later years, and Peck would deliver the eulogy at Niven's funeral.

There is no Navarone in real-life.

Although in the plot, Mallory is supposed to be fluent in German, Gregory Peck could not speak the language, and so his German lines are all dubbed by Robert Rietty. Peck was also dubbed when speaking Greek.

Because the stars were all too old for their characters, the movie was nicknamed "Elderly Gang Goes Off to War" by the British press.

Gregory Peck often said he was disappointed that so many viewers had missed how anti-war this movie was intended to be. Peck was a life-long pacifist, who strongly opposed U.S. involvement in the Korean and Vietnam Wars. He was also against joining World War II, until Adolf Hitler invaded the Soviet Union.

Some members of the Greek royal family and their entourage were extras in the café scene, as they were visiting the set on the day that scene was being filmed.

Gregory Peck later admitted that he felt miscast as Mallory, who was supposed to be English.

Although often regarded as an action movie, Gregory Peck said this movie was intended as a pacifist message like The Big Country (1958).

The plot went through so many twists, that Gregory Peck finally submitted his own version to Carl Foreman: "David Niven really loves Anthony Quayle, and Gregory Peck loves Anthony Quinn. Tony Quayle breaks a leg, and is sent off to the hospital. Tony Quinn falls in love with Irene Papas, and Niven and Peck catch each other on the rebound, and live happily ever after."

The last sequence shot was the actual setting of the bombs. With three days left to shoot, David Niven was felled by an infection from a split lip sustained shooting in the studio tank. As doctors tried to identify the infection so they could treat it effectively, the production ground to a halt for a month. Finally, Niven defied his doctors' orders and returned to the set to finish this movie before he had fully recovered. The relapse that resulted put him in the hospital for seven weeks.

There was reportedly much tension between many of the stars (particularly Gregory Peck and Anthony Quinn) early in the film's production, but the cast gradually bonded over endless games of chess.

For the scene where the commandos scale the nearly vertical cliff, the rockface was a painted backdrop laid out on the ground, so the actors were actually climbing over the studio floor and then the image was tilted in camera.

Kenneth More was originally cast as Miller, but was released from this movie (and his contract at Rank) after abusing and swearing at Rank chief John Davis during a BAFTA dinner at the Dorchester. He was replaced by David Niven.

Michael Trubshawe (Weaver) was David Niven's oldest friend. The two men served in the military together as young men, and Niven was later responsible for persuading Trubshawe to pursue an acting career. Niven also made it an inside joke to try to mention Trubshawe's name in as many of his own films as he could, usually as a reference to some unseen character.

Many viewers incorrectly assumed Gregory Peck's character was supposed to be an American.

The top grossing film of 1961.

The fifty thousand dollar fee, paid to Composer Dimitri Tiomkin, was the highest fee paid to a composer for a single feature film score up to that time.

The original 1961 roadshow release, used Technicolor prints made in London, which gave the movie eye-popping clarity, and disguised many of the imperfections of the sets and special effects. When it came time to turn out mass runs of prints for the general release, Columbia Pictures shipped the original negative to a bargain-rate lab in New York City, where it was reconfigured for normal Eastmancolor printing. This meant re-cutting the negative to insert standard opticals to approximate the Technicolor process' smooth dissolves, et cetera. No preservation separations were made, and the negative wasn't properly protected. Poor-quality dupe sections were soon patched in to replace damaged pieces of the negative. Eventually, two entire reels would have to be replaced in this way, after that, the New York City lab accidentally destroyed the originals through handling errors. Columbia Pictures also discarded the movie's original sound elements and stereo tracks. A collector's magnetic print was used to recover the original four channel stereo mix.

With a budget of six million dollars, at the time, this was one of the most expensive movies ever made.

Apart from James Darren, all of the actors were too old for their characters.

The screenplay differs drastically from Alistair MacLean's book, in terms of characters, including the identity of the traitor, and the two women who don't even appear in the novel. The two guides were actually men, but the women characters did more or less follow the novel.

David Niven fell ill during filming, and production was shut down while he recovered.

One of the Rhodian locations used in this movie has been renamed "Anthony Quinn Bay" after the actor was reported to have bought property nearby.

Throughout shooting, Gregory Peck suggested re-writes to Carl Foreman that would deepen his character. Most of his ideas made it into the movie.

The tanks used by the Germans in the movie were actually American. They included the M24 Chaffee and the M8 Greyhound.

Producer Carl Foreman brokered a deal with the Greek Army, where he had twelve destroyers, and over one thousand infantrymen at his disposal.

The initial two million dollar budget rose quickly thanks to the rigors of location shooting, including filming in areas that were only accessible by donkey, and the need to hire one thousand Greek soldiers to play the German Army.

James Darren was cast as Private Spyros Pappadimos in hopes it would get him out of the "teen idol" stage. However, the sequel to Gidget (1959) came out later in the year, starring Darren as Moondoggie.

Jack Hawkins was intended for a role in the movie, but was undergoing cobalt treatment for throat cancer.

There had been talk of Gary Cooper playing Mallory, but he underwent surgery for prostate cancer in April 1960 after it had spread to his colon.

Gregory Peck revealed, in a later interview, his bemusement at co-star Anthony Quinn's decision to wear a red undershirt, which was only somewhat revealed through most of the movie, but which became a glaring focal point when wet and placed against a most blue and gray background near the end of the movie.

Rock Hudson was considered for the role of Captain Keith Mallory. Cary Grant was also briefly considered, but was rejected as being too old at fifty-six.

"Yialo Yialo" ("Seashore, Seashore"), heard sung at a wedding celebration, is a Greek folk song about love and the sea. As with many provincial folk songs, verses are often improvised as it's sung. The first verse heard in this movie (asking the sea not to wake the singer's beloved) is standard, while the second verse, sung by actor and singer James Darren, is ostensibly improvised. The verse asks the mountains to bow down so that he can see his dearest love, "Anoula", and far-away home, "Rahoula". This improvisation came about as follows. Carl Foreman's production coordinator with the Greek government, Daniel Bourla, who also functioned as the producer of two shorts made on the filming of this movie, one directed by John Schlesinger, and one by Bourla, tried to obtain an affidavit from the Greek government certifying that Yalo Yalo was in public domain. The certification was issued, but it erroneously listed Bourla as its author. Whereupon, Bourla issued a release himself for the use of this song and added a needed additional verse to the song using the name Anoula (Anna being his girlfriend at the time).

James Darren was concurrently on honeymoon during filming.

Private Brown (Stanley Baker) is referred to as "The Butcher of Barcelona" by Captain Mallory, as a reference to his service with the Republican forces in the Spanish Civil War. In the 1930s, Carl Foreman, the Producer and Screenwriter of the movie, had been a member of the Communist Party, many of whose members fought for the Republic during the Civil War. Foreman was blacklisted during the early 1950s and moved to England, where he continued to work in the film industry. During the period of the blacklist, left-wing supporters of the Spanish Republic often were denounced for being "premature anti-fascists" for having fought against Franco, Hitler, and Mussolini before the U.S. went to war against the Axis two years after the collapse of the Spanish Republic.

For shots of the British Navy sailing the Aegean, the production rented battleships from the Greek Navy, even though all of their ships at the time were surplus U.S. ships.

For British prints, Richard Harris' use of the word "bloody" was replaced with "ruddy".

James Darren has fewer than ten lines of dialogue. His first line is "Watch out!" during the scene with Nicolai, the laundry boy.

Dean Martin and Sir Alec Guinness were considered for the role of Corporal John Anthony Miller.

When the movie was released, it was widely felt that a British actor like Richard Burton should have played Mallory.

Anthony Quinn was always Carl Foreman's first choice to play Stavros.

The original director was Alexander Mackendrick, but he was fired by Carl Foreman due to "creative differences" a week before shooting started, according to TCM.

There had been some concern that the cast would not get along, particularly since Anthony Quinn had a reputation for being difficult to work with. However, in the event things went smoothly, although according to Quinn Stanley Baker did not get along with the others. Some of the cast believed that Baker felt he should have been playing Mallory.

There was a sequel called Force 10 from Navarone (1978).

Andreas' revolver that he points at Mallory from behind the newspaper is an Enfield No 2 Mk I* (identifiable as the "*" modification by the lack of the hammer spur). It fired the anemic .380/200 service round, and is widely considered to be one of the worst service sidearms ever foisted on an unwilling army.

1980s rock group Big Country borrowed from Dimitri Tiomkin's score to create the guitar riff on their hit "Fields of Fire".

J. Lee Thompson's handling of intimate drama on Tiger Bay (1959) and of large scale action setpieces on North West Frontier (1959) landed him the director gig.

The character of Mallory is a New Zealander in the novel, although his nationality is never mentioned in this movie.

When Mallory says of Stavros: "He's from Crete; those people don't make idle threats", he's inverting the famous quote by the Cretan philosopher Epimenides, that "all Cretans are liars". The end of the movie reveals which of the two is right.

Lead character Mallory is chosen for the mission specifically because of his mountain climbing prowess, the name for the character may well have been based on real-life mountaineer George Mallory, who died trying to summit Mount Everest in 1924 (his body would remain, undiscovered, upon the mountain for another seventy-five years) Incidentally, real-life Mallory's climbing partner's name was Andrew "Sandy" Irvine, which, if you include the nickname, has the initials of fictional Mallory's partner (A.S. for Andrea Stavrou) in it.

Gregory Peck was a decade older than his character.

According to the 50th anniversary book about the R.A.F.'s Battle of Britain Memorial Flight the Flight's Lancaster appeared in this movie.

For the scenes set on the Aegean, the company rented a fifty-five-foot boat, the Maria, from local fishermen.

J. Lee Thompson's first American feature was also his opportunity of working with some of the biggest Hollywood stars.

Gregory Peck was considered too obviously unathletic to play a mountaineer.

The team is recruited from various British Army outfits, which is identifiable via their cap badges. Miller (Niven) wears the cap badge of the "Durham Light Infantry" Franklin (Quayle) wears the insignia for the "9th Queen's Royal Lancers". Brown (Baker) wears the insignia for the "Queen's Own Royal West Kent Regiment." Major Baker (Cuthbertson), who houses the team before they head out, wears the "Royal Regiment of Artillery" insignia.

The scene near the end of the movie, where the guns fire on the approaching British ships show the gun crew dressed in anti flash gear covering their ears in a synchronized movement. This was used as the basis for the viewing mice in A Grand Day Out (1989) featuring Wallace and Gromitt, where they don their sunglasses as the rocket was taking off.

Gregory Peck and James Robertson Justice also shared screentime in Moby Dick (1956): Peck as Captain Ahab, and Justice as Captain Boomer. They also starred together in Captain Horatio Hornblower R.N. (1951).

The only Best Picture Oscar nominee that year not to be nominated in any of the acting categories.

One of the warships in this movie, then a training ship in the Hellenic Navy known as Aetos (D-01), was previously the Cannon class destroyer escort U.S.S. Slater. The ship was later returned to the U.S., and the U.S.S. Slater is now a museum ship in Albany, New York.

The movie's maps were created by Halas and Batchelor, a British team best known for their animated movies.

James Mason was originally to co-star as Miller.

CASTLE THUNDER: Heard as the gun cave explodes.

On seeing this movie, Sir Winston Churchill approached Producer Carl Foreman about making a movie version of his autobiography, "My Early Life", It would be another eleven years before Foreman would guide it to the screen, as Young Winston (1972), directed by Sir Richard Attenborough, seven years after Churchill's death.

When Carl Foreman first announced this movie, Maria Callas was to play the female lead.

The only Best Picture Oscar nominee that year to be also nominated for Best Special Effects.

The last few minutes showing the trolley going down the runners, triggering the explosion, the explosions, and the British ships sailing through safely were used for the introduction of the sequel Force 10 from Navarone (1978).

Marlon Brando passed on the role of Corporal Andrea Stavros.

"Yialo Yialo" ("Seashore, Seashore"), sung at a wedding celebration in the film, is a Greek folk song about love and the sea. As with many provincial folk songs, verses are often improvised as it's sung. The first verse heard in the film (asking the sea not to wake the singer's beloved) is standard, while the second verse, sung by actor/singer James Darren, is ostensibly improvised. The verse asks the mountains to "bow down" so that he can see his dearest love, "Anoula", and far-away home, "Rahoula".

There are characters in the supporting cast named Grogan, Weaver, Barnsby, and Baker, all names that turn up attached to quite different characters in other, unrelated movies written by Carl Foreman.

Near the end of the film, when the Germans gain access to the gun turret again, they can be seen using metal detectors to look for mines directly over the metal railroad tracks that supply wagons use to bring supplies to the gunners. The rails would render the metal detectors useless for finding anything else except the rails.

Once Anna is revealed as the traitor, Miller finishes his argument by saying "Q.E.D." "Q.E.D" is an old Greek and Latin phrase, "quod erat demonstrandum", meaning "which is what had to be proven" and is used to drive the point home.

It is interesting that Stavros smokes a pipe throughout the film. That being said you would think he would have a second one. A pipe sours quickly if smoked constantly.