The famous scene in which Jim (John Gilbert) teaches Melisande (Renée Adorée) to chew gum was improvised on the spot during filming. Director King Vidor observed a crew member chewing gum and later recalled, "Here was my inspiration. French girls didn't chew or understand gum; American doughboys did...Gilbert's efforts to explain would endear him to her and she would kiss him...[It was] one of the best love scenes I ever directed." Gilbert also claimed that he did not expect Adorée to swallow the gum, which proved to be the scene's comic highlight.
The movie was a huge hit. When MGM discovered that a clause in director King Vidor's contract entitled him to 20% of the net profits, studio lawyers called a meeting with him. At the meeting, MGM accountants played up the costs of the picture while downgrading the studio forecast of its potential success. Vidor was persuaded to sell his stake in the film for a small sum. The film ran for 96 weeks at the Astor Theater and grossed $5 million (approximately $50 million in 2003 dollars) domestically by 1930, making it the most profitable release in MGM history at that point. Said Vidor, "I thus spared myself from becoming a millionaire instead of a struggling young director trying to do something interesting and better with a camera."
The film takes place from April 1917 to the Spring of 1919. The battle scene was based on the WWI Battle of Belleau Wood, which raged for most of the month of June 1918. US forces suffered nearly 10,000 casualties, including 1800 killed. Laurence Stallings, who wrote the original scenario for "The Big Parade," served as a Marine Captain and lost a leg in this battle.
King Vidor recalled, "I timed the march of the U.S. youth into battle and possible death as a slow, measured cadence with the muffled beat of brass drums heralding doom -metronome to simulate exactly the gait of the soldiers."
Due to Hollywood censorship of the time, title-writer Joseph Farnham had to tone down the salty dialogue of the American soldiers. For example, he was required to substitute "b------s" for "bastards." Yet in another scene, he was allowed to have John Gilbert shout (in all caps) "GOD DAMN THEIR SOULS!"