Many long nights were spent filming the siege scenes. Loudspeakers were installed around the battlefield and fort so directions could easily be given to the hundreds of cast and crew. One night after many long hours, Mann shouted over the speakers, "What's that orange light? Turn out that orange light!" After a pause, another voice came over the speakers saying, "That's the SUN, Michael."

Wes Studi claimed in a 1996 interview that he and several of the other Native American actors spoke their lines in their own native languages. When Magua argues with the Huron Sachem in the Huron village, Studi speaks his native Cherokee, which is mostly unintelligible to Mike Phillips, a native Mohawk speaker. When Chingachgook talks with his son Uncas, Russell Means speaks Lakota Sioux to Inuit Eric Schweig.

Daniel Day-Lewis is well known for going to extremes in preparation for his roles. For this film he lived in the wilderness where his character might have lived, hunting and fishing and living off the land for several months prior to shooting.

By most accounts, each scene took at least 20 takes. Concerned about the growing cost, 20th Century Fox sent a representative to the set who did nothing but stand behind Michael Mann and say, "That's enough Michael, move on."

The shoot employed more than 900 Native Americans from all over the United States, mostly from the Cherokee nation.

Continuity

Hawkeye shoots a Huron who drops his gun. The gun falls off a rock and then in the next shot reappears on the rock for Hawkeye to grab as he runs by.

As they are climbing rocks along the river, Uncas looks back at Alice. His earring has changed sides (indicating that the shot was flipped).

When the colonials are at Fort William Henry and arguing with General Munro about releasing them to go back to their farms, Cora is shown standing in a doorway. When she is first shown, the doorway is over her left shoulder. In the subsequent shot, the doorway is over her right shoulder and she ultimately exits through this doorway.

As the British Army is retreating from Fort William Henry, Magua ambushes the British. At one point in the battle, Major Duncan Heyward is commanding a small group of British soldiers. Most of them get killed, and he begins to run away. The bayonet on his rifle disappears soon after he shoots one of the Indians.

Maj. Duncan delivers a dispatch to Gen. Webb. After he reads it, Gen. Webb puts it completely rolled-up and straight ahead in front of him. Subsequently it appears placed crosswise and a little open.



Factual errors

There are a number of scenes at Fort William Henry where Scottish or Highland soldiers in highland regalia are depicted, but there were no Scottish or Highland soldiers present. The two regiments present were the 35th Foot (Sussex) and the 60th Foot (Royal American) who wore conventional British Infantry uniforms, not highland.

The French are seen lighting the bomb fuses in their mortars and then firing the mortars, even though it was discovered in the Seven Years' War that the flash was sufficient to ignite the fuse on a bomb (and indeed safer).

Hawkeye first sees the bombardment of the fort on the far side of an island. There is no island in Lake George anywhere near the fort.

The colors for the British regiments at Fort William Henry are incorrect in this film. The bright yellow flag has Roman numerals XLII for 42nd Regiment of Foot, Black Watch. Not only was this unit not at Fort William Henry historically, they were in Albany over 60 miles away, their regimental color was a brownish-yellow called buff and not a bright yellow. This second flag, a blue regimental belonging to the 35th Regiment of Foot, is also incorrect. Their flag had a rare and distinctive orange color, hence their nickname the Orange Lilies.

Everybody shoots and shoots and shoots, but nobody ever reloads. Those things actually fired one shot before needing to be reloaded.



Revealing mistakes

Gray rock-textured canvas, presumably covering modern trail signs or graffiti, is clearly visible in final scenes. Hawkeye bumps a canvas while running through an underpass, and a larger portion is visible as he returns to embrace Cora after Magua's death.

When Chingachgook hits Magua's arm with the war club, the club bends, showing that it was actually rubber.

(around 1:36:01) Hawkeye brushes against a rock which is in fact a canvas prop.

When Major Heyward and Cora Munro first meet and discuss marriage, there is a large sheet on a washing line flapping violently in the wind. However, none of the three characters in this scene is remotely affected by the wind.

At around 25 minutes, at the site of the Cameron's burned-out cabin, the prone body of Alexandra shows some breathing motion as Uncas lifts his hand away from her arm. Then, immediately on the next shot, you can see her on the far left of the screen already in a different position.



Anachronisms

As the British are leaving Fort William Henry, two buses are visible in the background as the British General rides by.

When Hawkeye is hunting at the beginning of the movie, there is a chain link fence in the background.

The flare launched from Fort William Henry during the bombardment scene was equipped with a parachute to provide longer use. This type of flare was not invented until shortly before the First World War.

When the British leave the Fort, a propane gas bottle, a plastic box and bucket made of stainless steel can be seen as the soldiers go down the ramp.

Telephone pole visible on the left side of the screen when the argument over the burial takes place.



Audio/visual unsynchronized

When Cora, Alice and Duncan have been taken prisoner by Magua and his men, the branch that Cora "breaks" is broken before she falls into it.

Duncan can be heard translating one of the lines from French before it is spoken.

When Major Heyward's company enters the forest for the first time, the drum tempo does not match the marching of the soldiers.



Crew or equipment visible

If you look very carefully during the opening, just as the elk emerges from the trees, you can see a man wearing a red hat, moving right next to the elk.

When the troops are leaving the fort there are two big red-and-white buses as well as a blue-and-white umbrella on the beach.

Diver visible at the bottom of the waterfall.

After Fort William Henry has surrendered, the assistant director is visible at the bottom of the screen, wearing a blue baseball cap and waving a megaphone.



Plot holes

When Colonel Munro learns that General Webb has sent reinforcements to another fort only 12 miles away, he orders that a runner be sent. On clear, windless nights, the sounds of cannon fire can travel up to 50 miles. So General Webb would have known that Munro's fort was under attack.

Magua states multiple times that it is his intention to destroy the family line of Col. Munro. However, when he finally catches up to Cora and Alice under the falls, he simply takes them as captives.