Billy Bob Thornton's character, "Longhair Jim" Courtright, was actually killed in a gunfight in front of the White Elephant Saloon in 1887. Each year, on the anniversary, the gunfight is reenacted on Exchange Street in front of the present-day White Elephant Saloon, in the Historic Fort Worth Stockyards.
Tom Hanks plays General George Meade in a flashback to the Civil War. Gen. Meade was famously known for defeating Robert E. Lee in the Battle of Gettysburg.
On April 9th, 1865, Lee ( General Robert E. Lee) surrendered to Grant (General Ulysses S. Grant) in the home of Wilmer McLean in the village of Appomattox, marking the end of the American Civil War. April 9th, 1883 is current date as stated in River (2021) and the eighteenth birthday of Elsa Dutton. The first battle of the Civil War - Bull Run / Manassas - was fought on Wilmer McLean's property there. Trying to get away from the war, he moved to Appomattox Court House, Virginia. In a case of extreme irony, Wilmer McLean would later state that the Civil War began in his back yard and ended in his parlor.
The episode title is a reference to Yellowstone Season 2 Episode 8, "Behind Us Only Grey."
The wild herd includes Herefords - a breed imported from Britain. The first of this breed in Texas arrived in In Fort Worth some seven years before this story takes place. The owners, who had purchased them in Chicago, immediately drove them to Henrietta - some 85 miles to the northwest of Fort Worth. Considering the expense, it is doubtful they would have allowed any to stray, and most likely not forty miles east, where the protagonists might find them but it is not beyond imagining.