Paper clips were not patented till 1867.
When the steamboat is shown departing the landing, and its whistle scares the horses, the film is being run in reverse (smoke is seen going *into* the smokestacks).
In the scenes where the cannons fire 30 rounds, some of the cannons fire before their fuses are ignited.
Col. Brackenbury is supposedly in command of the 5th New York Volunteer Infantry regiment, which, in reality, was an elite "Zouave" regiment with very distinctive uniforms. In this film, the soldiers are seen wearing regular Union uniforms.
From an opening title card, the film begins in the spring of 1862. Right after the inquest, Gen. Willoughby quotes Gen. Sherman as saying, "War is hell". That did not occur until September of 1864.