John Wayne's character in this movie, Major Daniel Xavier Kirby, was based on Captain John Lucien Smith, USMC Ace who was Commanding Officer in the Marine Fighting Squadron 223 at Guadalcanal in 1942 during World War II. Smith was a Medal of Honor recipient in 1943 and a leader of the "Cactus" Air Force. Smith, a wildcat fighter pilot, shot down nineteen Japanese airplanes over Guadalcanal in 1942. Smith's achievements and commendations were well known to the public prior to this film being made. Smith was eventually promoted to the rank of Lieutenant Colonel and likewise, Wayne's Kirby character is also promoted to the same rank in this movie. Moreover, there is also a physical likeness and resemblance between Wayne and Smith.
Robert Ryan was cast by director Nicholas Ray because he had been a boxer in college and believed that he was the only actor that could play opposite John Wayne and "kick Wayne's ass."
Even though this film is in color, the RKO Studio's film logo seen at the beginning of the movie is in black-and-white.
Marines got the nickname of "Leathernecks" from the fact that early uniforms had a collar made of leather which was intended to protect the throat from knife wounds.
The fighter planes seen in the early part of the film are not the actual Grumman F4F Wildcat planes which were part of the Guadalcanal air campaign but Grumman F6F Hellcat planes. Hellcats were more readily available at the time the movie was made in 1951 as not many Wildcats had actually survived World War II. Moreover, Hellcats painted white and red also doubled as enemy Mitsubishi A6M Zero fighter planes of the Imperial Japanese Navy Air Service (IJNAS).
The film utilized actual color aerial battle footage. According to the book "Brassey's Guide to War Films", this movie utilized combat footage from newsreels of the Korean War the Korean War was fought in its entirety between 1950-1953 but the footage would be circa 1950-1951 due to the production dates of the film. Yet this is a World War II movie about the Battle of Guadalcanal which predates the Korean War.
The film's dedication states: "Dedicated to the United States Marine Corps, and especially to Marine aviation. Appreciation is gratefully acknowledged for their participation and assistance which made this picture possible."
The Leathernecks of the film's title is military slang. Leatherneck is a common nickname for marines of the United States Marine Corps (USMC).
The squadron's designation in the movie was VMF-247 but in the real life campaign the movie was based on the designation was VMF-223. VMA 223 stands for Marine Attack Squadron 223. This was the United States Marine Corps fixed wing attack squadron that comprised mainly AV-8B Harrier (V/STOL) jets. It has been active since 1st May 1942 and is still presently today an active air force squadron.
There was some controversy over the casting, since both John Wayne and Robert Ryan were clearly much older than real pilots during World War II.
This film is about marine pilots fighting in the Battle of Guadalcanal. Guadalcanal is situated in the Solomon Islands in the Pacific Ocean, north-east of Australia. Its local name is Isatabu and contains the country's capital, Honiara. The island is humid and mostly made up of jungle with a surface area of 2,510 square miles or 6,500 square kilometers. Guadalcanal was named after Pedro de Ortega's home town Guadalcanal in Andalusia, Spain; de Ortega worked under Alvaro de Mendana de Neira who charted the island in 1568.
This is a Howard Hughes production as the opening credits declare. It is well known that Hughes himself was an aviation aficionado who also produced Hell's Angels, Sky Devils and Jet Pilot (1957), the latter of which also starred John Wayne.
This movie is often considered merely another assignment of Nicholas Ray's at RKO for Howard Hughes to prove his political and professional alliance during the Red Scare. A blatant pro-war movie that Hughes cared about and Ray did not, Ray disagreed with the film's politics and is said, along with Robert Ryan, to intentionally over-act. Ryan and Ray, who were leftist liberals, constantly fought against John Wayne and Jay C. Flippen, who were conservatives and supported the Blacklist.
This was Nicholas Ray's first film in color.