Justin Torrence, who played Robert Rogers, returned to do stunts later on in the production. Though he shaved his beard, he can be seen in the background of some shots during the battle around the flour fort.
In reality, Henry Bouquet and Anne Willing didn't end up together, and their brief romance was prior to the Seven Years War. After the events of Bushy Run and Fort Pitt, Bouquet took an assignment in Florida and ended up dying of Yellow Fever. In an early draft of the script, Bouquet received word from Ourry while at Fort Carslile that Anne was betrothed to another man. Later in the same draft, Bouquet dies of Yellow Fever at his post in Florida, hallucinating that the nurse attending him is his lost love Anne Willing. Though this more accurately depicted Bouquet's true history, it was decided early on in production that this would leave the audience unsatisfied, thus the story was altered.
Angus MacFayden was approached to play the role of Graham but was unavailable due to scheduling conflicts. He then offered to reprise his role as Robert Rogers, after playing the same historical character in TURN: Washington's Spies (2014), though this film takes place 15 years prior to the events of that series.
All three forts featured in the film (Pitt, Michillimacinac, and Venango) were built as one large set with each side portraying a different fort. The backsides of the inner buildings of Pitt were dressed to double as the front of buildings inside Michillimacinac and Venango.
It is widely believed that Henry Bouquet used poison blankets to infect the natives of Pennsylvania with smallpox. While it's historically true that both combatants used this early form of chemical warfare, and General Amhearst did suggest this method of infection, there is no evidence that Bouquet followed through with it. Though Ecuyer of Fort Pitt did attempt to, he was unsuccessful.