Post-production took almost a year. The film was edited on an Avid, with an HD cut also maintained in Final Cut Pro. The 3D was made using Maya, XSI and Lightwave. The 2D composites were made with Shake, Inferno, Fusion and Combustion. The filmmakers prefer Macintosh, but large portions of the movie were made under Linux. Asset management was handled by custom software written in the Panorama development environment, made by Provue. Color management was handled by Truelight software. The film was scanned on a Northlight scanner and was recorded on the Arrilaser. Most of the film was shot at high speed, between 50 and 150fps (normally, film is shot at 24fps). The film was transferred to HD SR tape and quicktime, and HD quicktimes were the basis for the HD preview cuts. The working resolution for the film was 2K, at a working aspect ratio of 2.11:1 and a projected aspect ratio of 2.39:1.
The film was photographed almost entirely on a sound-stage in Montreal, using blue-screen and green-screen backgrounds. The only part of the movie not shot on the sound-stage was the shot of the Persian messengers appearing over the top of a hill as they gallop towards Sparta, which was shot on location in Los Angeles. However, even this shot was heavily manipulated in post-production.
The filmmakers used bluescreen 90% of the time, and greenscreen for 10%. They chose blue because it better matched the lighting paradigm (green would have been too bright) and because red garments (a la spartan capes) look better when shot over blue.
The script demanded that most of the male cast spend the majority of their screen time bare-chested, as per Frank Miller's original graphic novel. Therefore, in order to adequately present themselves as the most well-trained and marshaled fighting force of the time, the entire principal cast underwent a rigorous and varied training regime for 8 weeks prior to shooting, organized by Marc Twight, a world-record-holding professional mountain climber. During the regime, the same exercise was never repeated twice, thus preventing the body from adapting to any one type of exertion. Gerard Butler has stated that the training was the most difficult thing he has ever had to do in his life, and when it was over, Twight admitted that he pushed the actors as hard as he's ever pushed anyone before, including himself.
The quote, "Then we will fight in the shade," is an actual one from history, spoken by the Spartan warrior Dienekes when warned about the enemies' arrows. It is also used by Greeks today as emblems on soldier uniforms. (Greek: "Tha palepsoume sti skià.")
The line "Come back with your shield, or on it" was a common phrase said by Spartan women to their sons and husbands. It was common Spartan practice to bear the dead soldiers on their shields. The phrase "Come back with your shield" was a reference to the fact that a soldier who showed cowardice would usually drop his very heavy shield as he ran away in order to escape faster.
When he was a child, Frank Miller saw the Rudolph Maté film The 300 Spartans, with Richard Egan as King Leonidas, and was deeply affected by it. He has explained that the film altered his perception of the 'Hero' concept insofar as he came to realize that the hero didn't always win and that sometimes, to be a hero, one must sacrifice oneself. Ever since he saw the movie, he has been fascinated with Thermopylae.
According to an interview with IGN.com, director Zack Snyder says that fighting styles and formations (particularly the Spartans' phalanx) were purposefully changed - making them historically inaccurate - so they'd "look cool" and work better for movie purposes.
In an effort to get the studio executives to commit to making the movie, Zack Snyder and his team scanned every image from Frank Miller's graphic novel into a computer. They then removed all of the dialogue and descriptive prose, and added simple animation to each frame (such as burning fire, moving clouds, sparkling eyes etc.). They then edited these shots together into what amounted to an animated comic strip, and Snyder hired his friend Scott Glenn to record a voice-over narration for the piece. Snyder brought the film to Warner Bros., but they said they needed more to convince them that the movie could work. As such, he decided to shoot a live-action 'test' - a 90-second 360-degree continuous shot featuring a single Spartan killing several Persians. The combination of the animated comic images and the test convinced Warner Bros. that Snyder and his team were capable of making the movie. An extract from the animation as well as the entire test can be found as an Easter egg on disc 1 of the 2-Disc special edition DVD of the film.
Shortly after its release, Iranian bloggers and journalists were outraged by the movie. With headlines like "Hollywood Declares War on Iranians", they chastised the movie for its monstrous portrayal of the ancient Persians, ancestors of modern Iranians. A cultural adviser to President Mahmoud Ahmadinejad called it "American psychological warfare against Iran." Thus far, no mention has been made of the opening or closing scenes, which reveal that the Persians' portrayal is a result of the story being told from a Spartan's point of view, rather than an omniscient, contemporary viewpoint.
Queen Gorgo had, indeed, said the line, "Because only Spartan women give birth to real men" but not to the Persian messenger. According to the Greek historian Plutarch (in book III of his Moralia, called "Sayings of the Spartans") she said this phrase to an Athenian lady who asked her, "Why can Spartan women speak amongst men?".
When the narrator describes the Persian confusion with the troops at the rear wishing to advance and those in the front line wishing to retreat, he uses lines from the poem "Horatius" by 'Thomas Babington Macaulay', written in the 19th century about a small Roman force that held a narrow bridge against a much more numerous enemy. From the poem: "Was none who would be foremost to lead such dire attack: But those behind cried 'Forward!', and those before cried 'Back!'"
The movie never claims to be historically correct, something which is addressed at length in the documentary The 300: Fact or Fiction? on the 2-Disc Special Edition DVD. The movie is based heavily on Frank Miller's 1998 comic book mini-series, also entitled "300". In the documentary Miller openly admits that he made many radical changes to the history and director Zack Snyder admits to making further changes. Snyder states that he was more concerned with making a film which would appeal to a wider audience, and creating an exciting and visually stunning action movie rather than a typical historical epic. Indeed, he further points out that the film is a subjective narration by Dillios (David Wenham) in an effort to spur his men, and as such, the narrative cannot be trusted as historically accurate or wholly objective. Snyder acknowledges that Dillios is not a man to allow truth get in the way of a good story, and that the point of the depiction is that it is specifically the Spartan perspective of the battle. In particular, Snyder cites the depiction of the Immortals. The Immortals were a real battalion, but they weren't demons, they were just ordinary men. However, in Dillios' narration, it is much more dramatic and heroic if the 300 fought off the attack of 10,000 demons rather than 10,000 men. As both Miller and Snyder argue, the film is not a realist piece.
The line "Come and get them!", said by Leonidas in response to the Persian demand for the Spartans to surrender their weapons, is also a historical quote (according to ancient historian Herodotus), which was adopted as the motto of the Greek Army's 1st Corps. (Greek: "molon labe")
Shortly after the film was released, there was considerable controversy as regards Tyler Bates's score. It was pointed out that Bates' music heavily borrowed from Elliot Goldenthal's score for Titus. In particular, Bates' "Remember Us" is identical in parts to Goldenthal's "Finale", and "Returns a King" is very similar to "Victorius Titus". There was talk of an impending lawsuit, however, on 3rd August 2007, Warner Bros. Pictures acknowledged on the film's official website, "a number of the music cues for the score of 300 were, without our knowledge or participation, derived from music composed by Academy Award winning composer Elliot Goldenthal for the motion picture Titus. Warner Bros. Pictures has great respect for Elliot, our longtime collaborator, and is pleased to have amicably resolved this matter." As a result, the Blu-ray re-release, titled "300: The Ultimate Experience" features the note "Derived in Part from Preexisting Compositions Not Authored by Tyler Bates" beside the composers credit.
The unique look of the film was produced in post-production by using an effect nicknamed "the crush". As producer Jeffrey Silver explains on the film's official website - "you crush the black content of the image and enhance the color saturation to change the contrast ratio of the film."
In the movie, some of the Spartan men can be seen with trimmed beards or no facial hair at all. However, in accordance with ancient Greek custom, it was completely unacceptable to shave one's beard, lest they be marked as effeminate (even though someone could shave their moustache as long as they left the beard alone). The only time a beard was shaved was as the mark of a coward or as a sign of mourning.
The character of Dilios (David Wenham seems to be, in part, based on the actual, historical figure of Aristodemus - according to historian Herodotus, he was the sole Spartan survivor of the battle of Thermopylae, having been dismissed from the force by Leonidas on account of an eye infection (not a wounded eye). Rather than returning to lead any Spartan force, however, Aristodemus was considered a coward until he redeemed himself by fighting, partially blind, and dying in the battle of Plataea a year later (the battlefield on which Dilios is seen delivering his rousing speech that is the narrative of the movie), where the Persian invasion was finally crushed.
King Leonidas derides the Athenians as "boy-lovers." It was, in fact, the Spartan army that was erroneously thought to encourage homosexual relationships among soldiers due to the fact that a Spartan male would live with his fellow soldiers till about 30 years old.
Military strategists have pointed out that the way to break the Spartan formation was to use artillery. If heavy missiles such as stones were rained on the Spartans it would have enabled the Persians to destroy them from a distance. However, catapults were not invented for another 200 years.
The reason the Spartan civilization fell was because it refused to change. Although strong militarily, they would not adapt their culture to a changing world. For example, they refused to coin money. This meant that most other nations refused to trade with them, and they had a hard time paying for their own equipment. They also treated other people as harshly as they treated each other, which earned them more enemies than they could fight.
Leonidas' final words to Ephialtes, "may you live forever", in addition to being an insult against the the hunchbacks' desire to be a Spartan (whose greatest glory is to die in the battlefield, and to whom longevity is undesirable), is also an allusion to the fact that, following the events at Thermopylae, the word "ephialtes" entered the Greek language to mean "nightmare", or to describe someone as the ultimate traitor.
The entire Senate subplot, including the rape of Queen Gorgo, was invented for the film and does not appear in Frank Miller's original comic books. Miller's comic book miniseries also has a lesser emphasis on monsters, with Ephialtes the hunchback, the immortals, all the animals, and the Ephors being the only "creatures" in the original story.