Factual error: The Liberty Bell is depicted ringing as the Declaration of Independence is being signed on July 4 (a mistake itself) in the film. The bell actually did not ring on that date, but on July 8, when the Declaration had been returned from the printer and unveiled to the public.
Continuity mistake: Look very closely when Mr. Thomson is taking the vote by a show of hands on whether or not to make the vote on independence unanimous. Of the delegates who say nay, Thomson points to the direction of Adams first, however, Hopkins is the first delegate shown. Thomson points to the direction of Hopkins last, but Adams is the last delegate shown. Maybe this part was reversed, or the filmmakers screwed up.
Edward Rutledge: Mr. Adams is now calling our black slaves "Americans." Are they, now?
John Adams: Yes, they are. They're people, and they're here. If there's any other requirement, I've never heard of it.
Edward Rutledge: They are here, yes. But they are not people, sir, they are property.
Thomas Jefferson: No, sir, they are people who are being treated as property!
[After hearing Dickinson bang on a desk.]
Benjamin Franklin: Please, Mr. Dickinson, but must you start banging? How is a man to sleep?
John Dickinson: Forgive me, Doctor Franklin, but must you start speaking? How is a man to stay awake?
John Dickinson: We'll promise to be quiet, sir. I'm sure everyone prefers that you remain asleep.
Benjamin Franklin: If I'm to hear myself called an Englishman, sir, I assure I prefer I'd remained asleep.
John Dickinson: What's so terrible about being called an Englishman? The English don't seem to mind.
Benjamin Franklin: Nor would I, were I given the full rights of an Englishman. But to call me one without those rights is like calling an ox a bull. He's thankful for the honor, but he'd much rather have restored what's rightfully his.
John Dickinson: When did you first notice they were missing, sir?