The circumstances of Caesar Rodney's ride are historically inaccurate. Rodney suffered from asthma and skin cancer, but he had not returned to Delaware because he was dying. As a brigadier general in the Delaware militia, he was in Sussex County monitoring Tory activity when he received word that the vote on independence was about to take place. Changing horses several times, he rode all night, eighty miles through a thunderstorm, to reach Philadelphia in time to cast his vote. He remained almost continuously in public service until his death in 1784.
Incorrectly regarded as goofs
While attempting to write the Declaration in his apartment, Jefferson throws the paper about and finally tosses his quill and picks up the violin. As Adams and Franklin enter the apartment, the quill has reappeared in the inkwell on the desk in front of Jefferson. But the change in lighting (from darkness to broad daylight) indicates that many hours have passed between the two moments. Besides, in the quill pen era writers always kept multiple quills at hand because they wore out or needed resharpening with great frequency.
The beginning of the film takes place in early June, 1776 in Philadelphia. There are several references to the heat, and several delegates are clearly sweating. After a squabble breaks out during the debate, John Hancock orders McNair to remove a dog from the room because it smells bad. As McNair complies, Hancock shouts, "Christ! It's hot!" and Thomas Jefferson sits on a sill by an open window to read a book. In the next scene, the dog is out on the sidewalk. It barks twice, and you can see its breath.
At the Congress, John Adams says "Benjamin Franklin smote the ground, and out sprang George Washington, fully grown and on his horse. Franklin then electrified them with his miraculous lightning rod and the three of them - Franklin, Washington, and the horse - conducted the entire Revolution all by themselves". John Adams made that speech in April 1790 at Franklin's funeral.