During the battle at James Island, within a second, and without orders to attach them, all of the 54th Regiment have their bayonets mounted for the charge.
During the first battle, somehow bayonets are fixed before they charge. When they first form the line in that scene, bayonets are obviously not fixed. There is never an order given to fix them.
At James Island, Thomas's bayonet sticks out of the Confederate soldier's chest, with Thomas right behind him. In the next shot of the soldier's back, there is no wound, bayonet, rifle, or Thomas.
When Shaw is wounded at the battle of Antietam, he crawls up against a dead soldier. When Rawlins finds him, he is lying next to a completely different man.
When Trip scuffles with the white soldier on the road, and Sgt. Major Rawlins walks up to break it up, his coat is unbuttoned, with his undershirt clearly visible. When the scene cuts to his dialogue, his coat is buttoned all the way up.
In real life, the 54th Massachusetts didn't accept runaway slaves because Gov. Andrew wanted it to be an elite unit. Nearly all of the men could read and write. One private was a doctor.
In the film, Shaw's body is dumped into the mass grave with his red sash. The red sash was taken by a private, and a Ft. Wagner officer bought it from him later. He returned the sash to Shaw's widow 20 years later.
In the movie, Shaw is surprised when the men refuse pay that was reduced because they are a "colored" regiment, though he eventually joins them in their refusal. In reality, Robert Gould Shaw came up with the idea himself.
In the film, Robert Gould Shaw receives the request to be Colonel of the 54th Massachusetts while at a party in Boston, and accepts immediately. In real life, he refused command at least twice, feeling unworthy. He finally accepted after some convincing by his friend Charles Russell Lowell, commander of the 2nd Massachusetts Cavalry.
In the film, the 54th Massachusetts Infantry Regiment trains through Christmas 1862, after the September 1862 Battle of Antietam. In real life, the 54th Massachusetts was organized in March 1863. Its first battle was James Island, South Carolina, on July 16, 1863, then Fort Wagner on July 18, 1863. The 54th went on to fight at Olustee, Florida (February 20, 1864), Honey Hill, South Carolina (November 30, 1864), and Boykin's Mill, South Carolina (April 18, 1865).
"The Bonnie Blue Flag" plays when the 54th returns from the Battle of James Island. The melody is "The Irish Jaunting Car," a British song from the Crimean War. Many songs on both sides of the Civil War used the same melody, including "The Bonnie Blue Flag" and "Arms of Abraham," a humorous song lamenting the experiences of a draftee in the Union Army.
The movie claims that "over half" of the regiment was lost during the assault on Fort Wagner. According to official records, the 54th sustained 272 casualties, closer to 40%. Of those casualties, 116 were fatalities, just under 20% of the men to storm the fort. In formal military terms, casualties include captured soldiers. If the 156 captured soldiers are included, it brings the total to over 50%.
Morgan Freeman's character was not too old to be recruited or conscripted into the Union Army in 1863. At the time, enlistment was limited to men between 18 and 45 years of age. Freeman was in his fifties when this film was made, but people aged much faster in the 19th century, especially outdoor laborers like his character.
A children's choir sings "My Country 'Tis of Thee." The lyrics date to 1831, and were popular by 1863.
In the opening scenes, when Shaw marches beside his soldiers toward the Antietam battle, the rank insignia on his epaulets change from that of a captain (two bars) to that of a second lieutenant (no insignia within the epaulet borders) because it's a flashback.
Several extracts from Colonel Shaw's letters to his mother, as heard in voice-over narration throughout the film, were actually taken from "Army Life in a Black Regiment," an 1870 book by Thomas Wentworth Higginson, who commanded the 1st South Carolina Regiment during the Civil War.
When Shaw finally loses patience with the Quartermaster, he marches in and demands 600 pairs of shoes and 1200 pairs of socks. After the initial interchange, Matthew Broderick says "Do you really think you can keep (pause) 700 Union soldiers..." The slight pause shows that Boderick momentarily forgotten his lines.
Shaw's family is shown as residing in Boston. Although that is where they came from, at the time of the Civil War the Shaw family was domiciled on Staten Island, New York to be near an eye specialist treating Shaw's mother. That explains why at the start of the film Shaw is serving in a New York, and not a Massachusetts, regiment.
The men's breath is visible the night before the big attack on Fort Wagner. That's very unlikely for South Carolina in July.
Shortly after Rawlins says the men need shoes, a soldier's shoe is slowly removed in front of Shaw. It shows how "worn out" the shoe is supposed to be, and the subsequently the damage to the man's foot. Only the midpoint of the sole appears worn-out.
When the children interact with Morgan Freeman and he waves goodbye, a modern wristwatch can be seen on one of the child's arms in the bottom right of the screen.
During the battle on James Island, right after the first skirmish between Confederate cavalry and Col. Shaw's men, Col. Shaw orders the men to 'Fire at will'. The soldiers repeat the order and then, immediately afterwards you can hear someone shout 'where's Will?'.
When the 54th Massachusetts march past the Southern plantation, a group of slave children run out to see them. After being greeted by Undertaker, they wave. One child wears a digital watch on his hand.
At one point Shaw tells Sergeant Major Mulcahy "at ease." During the Civil War, the command would have been "rest" or "in place rest."
After Col. Shaw is notified of his promotion, he and Maj. Forbes talk outside, and Maj. Forbes drinks champagne from a Dom Pérignon bottle. The champagne was first made in 1921 and released for sale in 1936.
When Rawlins is promoted to Sergeant Major, he is handed the insignia sewn onto blue cloth backing. The stripes of the era were individual stripes, and had to be sewn on one-by-one.
When the 54th first marches past a mansion in Georgia, a square concrete curb is visible on the left side of the road (to the soldiers' right).
During the singing of the Negro spiritual on the eve of the assault on Ft. Wagner, the key and tempo noticeably change when the soundtrack switches from playback to production sound (recorded on location).
As the 54th Massachusetts is preparing for battle at James Island, Rawlins shouts to the soldiers "All right men, form a firing line! Over here!", without moving his lips.
After Rawlins hands Trip a rifle, Trip fires it into the air with an audible "click" (as in no round loaded). The hammer is still in cocked position, meaning Trip never actually pulled the trigger, and the "click" was added in post-production.
When Pvt. Trip is being brought before Cpt. Shaw for desertion, the beatings of the drum are off.
During the final battle scene with the 54th forming up for the attack on Ft. Wagner on the beach, the ocean is to their left. This would mean that they were headed south instead of north. Fort Wagner was attacked from the south, so the Atlantic Ocean should be on the right.
When Colonel Shaw volunteers to lead the charge on Fort Wagner, he tells General Strong, "you should have seen us in action two days ago; we were a sight to see". The skirmish Shaw was referring to occurred on James Island, SC on July 16th, 1863. The charge on Fort Wagner occurred two days later, on July 18th. In the film, Shaw's conversation with General Strong takes place on the 17th, with the regiment resting that night and making the charge the next day. He should have said "you should have seen us in action yesterday."
When Maj. Forbes approaches Shaw to ask why he is being so hard on the men, he is outside and not wearing his uniform blouse (coat) or a hat. Neither would be acceptable at the time of the Civil War. In fact, modern military regulations require hats (covers) be worn whenever outdoors.
When Shaw goes to the Quartermaters office, he demands "600 pairs of shoes and 1200 pairs of socks." That wouldn't have been enough; the unit had 1100 soldiers at full strength.
When Shaw falls to the ground at Antietam, he lands on the corpse of a Union soldier, which blinks.
When handing out Enfields, John Rawlins says that they are ".57 caliber Enfields rifles." They're actually .577 caliber. The crate says .577 caliber as well.