Ray Harryhausen regarded this as his best film.

It took Ray Harryhausen four months to produce the skeleton scene, a massive amount of time for a scene that lasts, at the most, three minutes.

While filming footage of the Argo off the coast of Italy, shooting was interrupted when a replica of the Golden Hind sailed into view. The British television series Sir Francis Drake (1961) happened to be filming in the same location. Producer Charles H. Schneer shouted, "Get that ship out of here. You're in the wrong century!" at the British crew, dispelling any tensions that arose from both shots being lost.

After Ray Harryhausen received the Gordon E. Sawyer Award recognizing his contributions to the film industry at the Oscars' Science & Technical Ceremony in 1992, Tom Hanks, the host of the event, said, "Some people say Ciudadano Kane (1941) or Casablanca (1942). I say 'Jason and the Argonauts' is the greatest movie ever made."

After the success of Sergio Leone's El Coloso de Rodas (1961) (U.S. title: "Colossus of Rhodes"), it was decided to change the character of Talos into a living bronze giant. It would become one of Ray Harryhausen's most famous creations.

This British / American film was released in the waning years of the Italian-produced sword-and-sandal / mythological muscleman movies. Many of those productions dealt with Jason. Most unusual for the time was the casting of British actor Nigel Green as Hercules. Although he was very tall, Green lacked the bodybuilder physique that moviegoers were used to seeing for this character. The film may not have been able to match the scale of many of the European spectacles, but the elaborate special effects by Ray Harryhausen gave it the look of a more expensive production, contributing to its box-office success.

In the early stages of story development the twin sea monsters Scylla and Charybdis, a centaur, and the three-headed dog Cerberus were intended to appear.

Colchis, the location of the Golden Fleece, is an actual place on the east coast of the Black Sea, in western Georgia.

The voice of Todd Armstrong, who played Jason, was dubbed by British actor Tim Turner. Turner's voice was well known as the narrator of the '60s Rank series "Look At Life"'. He was also the narrator of trailers in many British films in the '50s, '60s and '70s, including the one for this movie, and provided the voice of Dr. Peter Brady, the titular hero of the popular late '50s British TV series, El hombre invisible (1958).

The skeletons' shields are adorned with designs of other Ray Harryhausen creatures, including an octopus and the head of the Ymir from A 20 millones de millas de la Tierra (1957).

Presumably in order to capitalize on the success of Simbad y la princesa (1958), Ray Harryhausen originally conceived of the film as "Sinbad in the Age of Muses". The story would still have been set in ancient Greece and would have involved Sinbad joining Jason in the search for the Golden Fleece.

Bernard Herrmann's score liberally utilizes the technique known as "self-borrowing", which involves reusing elements from his previous scores. Exact passage reuse is taken from scores for El hombre de Kentucky (1955), Duelo en el fondo del mar (1953), Operación Cicerón (1952) and others, and reworking of passages from Con la muerte en los talones (1959), Ultimátum a la Tierra (1951) and Vértigo (De entre los muertos) (1958) scores, among others.

The previous Ray Harryhausen films were generally shown as part of a double feature in "B" theatres. Columbia was able to book this film as a single feature in many "A" theatres in the United States.

Nigel Green (Hercules) and Douglas Wilmer (Pelias) would both later play Fu Manchu's arch-enemy Sir Denis Nayland Smith in films starring Christopher Lee as the Chinese criminal mastermind: Green in El regreso de Fu-Manchú (1965) and Wilmer in Las novias de Fu-Manchú (1966) and La venganza de Fu-Manchú (1967).

Contrasting with Bernard Herrmann's all-string score for Psicosis (1960), the soundtrack was made without a string section. This leaves the brass and percussion to perform the heroic fanfares, and the woodwinds along with additional instruments (such as the harp) to dominate in the more subtle and romantic parts.

The voice of Nancy Kovack, who played Medea, was dubbed by Eva Haddon, an actress well known on BBC radio.

Although Nancy Kovack (Medea) is billed second in the opening credits, she does not appear until 66 minutes into the 99-minute film.

Curiously, for the first time in the history of the trade name of Ray Harryhausen's "Dynamation" process, this film didn't carry the "Dynamation" brand, even in the opening credits. Early publicity materials for the film did, however, advertise it as being filmed in "Dynamation 90" (90 referring to the double 45-degree exposure in the sodium-light traveling matte process, used in this film and some of his previous films as well), but was reportedly dropped for being "too gimmicky". Additionally, the original pre-release prints carried the film's original title card, "Jason and the Golden Fleece" (which can be seen on the 1992 LaserDisc release by Criterion), before deciding on the film's eventual title, "Jason and the Argonauts", on March 1, three months prior to the film's release in early June.

Ray Harryhausen stated that he wanted to avoid the Italian "muscleman" stereotype present in films at that time when casting Hercules.

In early press material, Mario Nascimbene was credited as the music composer of this film. This was because Nascimbene was considered for the job of composer in case Bernard Herrmann turned it down (which, as it turned out, he didn't). In later interviews Nascimbene claimed he never heard of the film (most probably meaning Herrmann accepted the offer before Nascimbene could be approached). He did, however, go on to compose the music score for another Ray Harryhausen film, Hace un millón de años (1966), which was also directed by Don Chaffey (who directed this film).

King Aeetes' Guard Captain is dubbed.

Terence Stamp was considered for the role of Jason.

While the original release made no mention of Harryhausen's trademark Dynamation process, the 1978 re-release ads touted the film as being "in spectacular Dynarama."

The Argonaut named Polydeuces, the victorious boxer in the games, is more commonly known as Pollux. He and his twin brother, Castor, form the constellation Gemini. The sign of the zodiac called Gemini is also named for them. A part of the Argonauts tale that is not shown in the film is the story of Pollux and Amycus, King of Bithynia. Amycus challenged all men who were strangers in his land to boxing matches. If they were defeated by him they became his slaves. The King had never lost a fight. Pollux fought Amycus. He overcame the King's strength advantage with his footwork and jabs. He maneuvered Amycus into facing the sun, to obstruct his view. Amycus was spitting out blood and teeth when, in a rage he swung at Pollux but the latter avoided him. Pollux then struck Amycus to the ground and made him promise never to take slaves again.

John Cairney, playing 'Hylas' and Nigel Green, portraying 'Hercules' didn't actually get along at all during filming. Green would accuse Cairney of being very "effeminate" (Cairney was actually married at the time!) causing Cairney no end of trouble. The last scene they filmed together was the scene where Hercules and Hylas enter the treasure chamber, hidden in the plinth of the mighty Talos. The lighting used to give the treasure it's sparkling effect was very severe, and the following day, the actors began losing their vision. Frighteningly, both actors became temporarily blind and were hospitalised together in the same room for two weeks with their eyes bandaged. Fortunately their sight returned after their stay in hospital. During those two weeks of confinement with each other, they found they had a lot in common, and soon became fast friends. They remained good friends until the day Nigel Green died in the early 1970's.

"Jason and the Argonauts" was the only film Todd Armstrong made that was of any significance, during his career. He died in 1991 by his own hand.