Johnny tells Amsterdam that Bendrick the Cockroach "carries a germ" and "if you try to leave the gang, they say, he hacks up blood on you." The link between germs and disease wasn't known until after Robert Koch developed Koch's Postulates in 1876. Louis Pasteur's work, also published in the 1870s, completed the proof to the medical community, though it was called "the germ theory of disease" as late as 1914. In the 1860s, no ragamuffin street kid would have made the connection. The first recorded use of "germ" outside medical literature is John Tyndall's Fragments of Science for Unscientific People, published in 1879. Until then, "germ" was the part of a seed from which the plant sprouts.
In the opening scene, as Priest and Amsterdam ascend through the catacombs, a priest saying mass elevates the chalice while facing the people. Before the 1960s, priests said mass with their backs to the people.
Pink latex balloons decorate the scaffolding at the hanging. After Charles Goodyear's patent for vulcanization in 1843, some toy balloons were made from India Rubber spread thin in a solution of benzol or coal-naphtha, like the preparation used to waterproof raincoats and galoshes, and then vulcanized; they were thick, more like today's balls or the tough inflated pig bladders used in games before. The latex toy balloon was invented in 1931 by Neil E. Tillotson of Colebrook, New Hampshire. The originals were white or black; colored balloons came along even later, when dyes that would not dissolve the latex were developed.
Prior to the street battle in 1846, Priest Vallon recites a portion of the Prayer to St. Michael, "St. Michael the Archangel, defend us in battle! Be our protection against the wickedness and snares of the devil." The prayer was written by Pope Leo XIII in 1888.
The orders given to the Union soldiers responding to the riots are incorrect for their results. First, the officer in charge orders his column to halt with "Troop, halt!" However, a 'troop' is a cavalry unit, while the one in the scene is an infantry one. Depending on the rank of the officer and the size of his unit, the correct unit designation would be either 'company' or 'battalion'. The soldiers then level their rifles at the rioters on the command 'Present Arms.' 'Present Arms,' however, is a salute; 'Aim' was the proper command for aiming rifles in battle, and would only be given after another series of commands preparing the troops to fire and detailing the selected firing procedure, which is absent in the scene. Also, as the troops approach the mob, they halt before the word 'halt' is spoken. Troops, at least in that era, would march until the word is spoken; they do not stop in anticipation of the command, and this is still practiced in most modern armies as an essential part of discipline.
When the competing volunteer fire-companies are arriving at the house fire, one of the fireman can be seen wearing modern-day fireman's pants - perhaps an actual firefighter taking part as a safety precaution.
Just before the fight between Amsterdam and McGloin, an old man plays a modern hammer dulcimer. Period instruments would have been homemade, or built by carpenters used to working with furniture, and much more cumbersome.
When Tweed and Bill 'The Butcher' first talk in Tammany Hall, Tweed is feeding his birds as he confronts Bill's abuse of the Irish. The line beginning, "You may or may not know, Bill...", clearly does not match his lip movements.
When Bill The Butcher tells Boss Tweed about the streets that make up the Five Points, he names five. There were three; two continuing through and one ending. Little Water and Mulberry Streets were nearby, but not at the intersection itself.
When Amsterdam and Jenny are kissing after the dance, Jenny says she shouldn't take off her corset because it would take to long to re-lace. In an earlier scene, her corset had a metal closure called a busk in the front, meaning it didn't have to be re-laced every time.
When Amsterdam meets Johnny for the first time after coming back, they walk along the street and stop. As they talk, Amsterdam's satchel repeatedly moves from over his shoulder to under his arm and back between shots.
When Amsterdam is placed on the table, at the pagoda, Bill the Butcher straddles his chest and pounds a cleaver in the tabletop to the left of Amsterdam's head. With the cleaver still stuck in the table, Bill takes another cleaver from his belt and tosses it in the air. As the cleaver descends toward the table, the first cleaver has disappeared and the new cleaver lands in the original cleaver's place.
At the hanging, when the condemned man at left of screen is calling to his son and delivering his last words, all four men already have nooses around their necks. After he ends his speech and the hood is pulled down over his face, the nooses are dangling free in front of the other three men, and the hangman places the nooses back on their necks.
Just before the draft rioters break into the Schermerhorn house, as the family is sits down to eat, large celadon vases are visible in the dining room windows that overlook the street. Moments later, when the rioters smash through the windows, the vases have disappeared.
When Amsterdam first returns to the Five Points, he is walks alone. Monk stands in front of his shop and looks down at the town. To the right, Amsterdam and Johnny are taking before Amsterdam even meets him.
About 30 minutes into the film, when Amsterdam conspires with the Chinese men to murder Bill the Butcher, he shows them a sheet of paper. The second time, Amsterdam hands the Chinese man an unfolded sheet of paper. In the next shot, the sheet is folded, and the Chinese man must unfold it.
After Amsterdam stops Bill the Butcher's would-be assassin, they struggle on the floor. In the wide shot, the assassin's right hand is empty and lying across his stomach. In the next shot, his hand is lying across Amsterdam, and holds a pistol.
After Amsterdam wrestles the assassin, the assassin drops his knife in the wide shot, and it tumbles away. In the next shot, when Amsterdam crawls away with the pistol, the knife is back in the assassin's hand, and he drops it again.
Johnny is forced to meet with Bill, who is seated with 'Boss' to his right. During the scene, the frequent p.o.v. shots change from Bill to Johnny and back and shows 'Boss's' gaze not where it should be on several occasions.
When Amsterdam follows Jenny onto the tram after she steals his medal, her hand reaches into a man's jacket. In the next scene, she takes her hand from her lap, as if for the first time, and reaches into his coat.
When the Union soldiers take aim at the rioters, each man steps forward with his left foot. During the Civil War, on the command "aim" a soldier would step BACK with his RIGHT foot, bringing it behind his left. Stepping forward would desecrate "the line" (all-important in nineteenth-century warfare).
During the opening scene before the fight, 'Priest' Vallon recites the St. Michael prayer for his son. The year of the scene was set before the Civil War. The St. Michael prayer was not yet recited nor prayed until 1884 when it was written by Pope Leo XIII in 1884. It would of not been known or prayed as is in movie during the year of the scene took place.
In the closing credits of the film released in December 2002, the Twin Towers can be seen on the horizon in the distance. The Twin Towers were destroyed in the terrorist's attack on September 11, 2001.
In the final scene, the weeds grow over the tombstones and just before the fade out the wind blows the grass in front of the final gravestone left on the right. When this happens the tombstone flaps around, revealing it is foam or similar lighter than stone material.
In movie, the Five Points are Anthony, Orange, and Cross Streets. By the time the events in the movie take place, they had been renamed Worth, Baxter, and Park streets, in an effort to change the area's reputation. Most Five Points residents would have still known and referred to the streets by their original names.
During the Draft Riots, a voice sounds like it's coming through a PA system. Microphones were first developed in the 1870s as part of the telephone, and mics capable of being a loud PA system were not in regular use until the early 1900s. However, the voice begins when a telegraph is on-screen. The words are being sent over the telegraph, not shouted to the crowds during the riots.
When Jenny says to Amsterdam and Johnny "I'll leave you in the grace and favor of the Lord," Amsterdam is on the left and Johnny is on the right. When the camera pans back to them, Johnny is on the left and Amsterdam is on the right. The shot is a pan, not a jump cut. When Jenny says "grace and favor etc." Johnny has moved from Amsterdam's left side to his right side.
Before the opening battle, Priest and his followers stand in Paradise Square awaiting their adversaries. Bill's men appear from behind some buildings, with a number of large treetops behind them, as if a forested area is behind the square. After the battle, the camera pulls back to show the Five Corners district in the heart of mid-1840s Manhattan. As the shot zooms out and increases in altitude to reveal the computer-generated scenery, no CGI trees correspond with the trees built to represent the Paradise Square area.
Members of The Dead Rabbits dye red stripes on their shirts to show their alliance. The dye clearly ends at the seam that joins the sleeve to the shirt front, meaning This the fabric was dyed red before the shirt was sewn together.
When Amsterdam is outside of the draft office the first time, the red-haired man behind the draft officer smokes his cigar 4 or 5 times, but never exhales any smoke. Amsterdam is smoking right next to him, and his smoke is clearly visible.
Early in the film, a man in a striped shirt cleaves Priest Vallon in the left elbow from behind with a large curved blade. A cut-away shot shows Bill making a cutting motion at the exact same time. Vallon is holding his cross, and in freeze frame it's obviously him. Bill says "Priest" and takes several steps before he encounters Vallon for the first time during the fight. Vallon, who should be in agony from the blow to his arm, stands and turns towards Bill. Vallon's arm is nearly severed by the opening blow, yet there is no evidence of such a severe injury during the hand-to-hand fight with Bill. As Vallon dies, his coat has some blood in the area of his left elbow, but not enough for the injury as initially shown.
When Amsterdam is prepares for the final fight at the end of the film, his Saint Michael medal is wrapped around his hand, positioned on the front of his knuckles. Afterward, as he continues to gear up, he takes the medal and wraps it around his hand.
When Bill throws his cleaver into Monk McGinn's back, the prop cleaver bounces off the door frame (lower left of the frame) before Monk falls. Later, as Bill walks up to the collapsing Monk, the prop cleaver is on the ground.