In Congress, Samuel Adams seconds motions proposed by his cousin John. Colonies were not allowed to second their own motions.
The opening shot in Philadelphia shows the outside of what is now Independence Hall but the actors are discussing the material which was decided at the First Continental Congress. That meeting was not held at Independence Hall, but at Carpenter's Hall which is down the street.
When General Knox is seen moving the cannons by the Adams residence, it is raining and the shrubbery is in bloom. In fact, Knox moved the cannons between the months of December 1775 and January 1776, dealing with snow and ice-covered rivers.
General George Washington is shown wearing the blue and buff uniform of the style that he would wear throughout the war. However, the style of the collar on this particular coat is not historically accurate in that the two corners of the collar on the uniform should have been either buttoned to the top of the lapels or capable of being buttoned down (which would be evinced by two clearly visible button holes in the collar, one at each corner). While no regimental coat belonging to George Washington from the time of the revolution is known to exist today, every single artist who personally observed Washington during the war painted him in his uniform with the collar either actually buttoned down or capable of being buttoned to the lapel tops. Further, the buttoned down collar was the style fashionable and in common use by American soldiers and officers during the mid-late 1770s.
When Adams is detailing the death of his physician, General Warren (Dr. Joseph Warren), Washington hadn't yet been appointed as the head of the Continental army. In reality, Washington didn't even know of Warren's death until he heard en route to Boston, AFTER being appointed General. Adams only found out later that Warren died at Breed's Hill.
In one scene Abigail is scrubbing the wooden floors in an effort to avoid the pox. The microbial theory of diseases was not postulated until the 19th. century. However, in the 16th century, King Henry VIII was famously having the walls of his children's (especially his son, Edward's) dwellings washed down once or twice a day to prevent disease. It is not impossible that although not widespread, this practice was also followed by others down through history.
While John Adams is in Congress debating independence from Britain (in 1776), his family is shown receiving a crude inoculation against smallpox. While it was not until 1796 that Edward Jenner determined that immunity to the pox could be achieved by injecting people with material from a cowpox lesion (vaccination), a more primitive practice using the actual smallpox virus (inoculation) was known and had been in practice in the West since the early 18th century. It is documented that the Adams family was indeed inoculated against the pox.
Soldiers are shown in brown and red coats outside the meeting of the Continental Congress. The soldiers are "bookended," with the one on the left holding his musket in his right (outside) hand and the one on the right holding his in his left (also outside) hand. Both soldiers should be holding their muskets (at the order) in their right hands. Also, neither man should be wearing a belly cartridge box.
When Washington is seen in attendance at the first Continental Congress, he is wearing the uniform he will don as commander of the Continental army, a dark blue coat with buff facings and buff waistcoat and breeches. Washington in fact wore his Virginia Militia colonel's uniform, illustrated in the portrait by Charles Willson Peale which was a blue coat with red facings and red waistcoat and breeches. Given the otherwise meticulous attention to costume accuracy, this is an unfortunate error.
Obvious modern reproduction pewter tankard in the Adams' city residence. Period pewter was cast in molds and then finely hand-smoothed if needed, leading to an evenly smooth surface - including the vessel's bottom. Most modern pieces have bottoms hastily smoothed with a lathe machine. The lathe leaves telltale concentric rings - which shine forth while young Charles shows the vessel's bottom to the camera as he takes a drink at the family table.