Factual error: As Ben is clinging to the staircase while it is falling apart, there is a close-up of a nail being pulled out of the wood. This nail is round-headed, rather than square as it would have been over 200 years ago. It's also shiny instead of rusty, which indicates that it's galvanized. Galvanization as an industrial, metal-preservation process was not patented until 1837, and was not used in building materials until well into the late-1800s. Since the film states the staircase was made by "the Founding Fathers, " and there was no galvanization of iron nails in any industrialized nation in 1780s-1830's, this is a huge anachronism.
Factual error: When Dr. Chase receives the Washington campaign button from Ben Gates, she immediately picks it up with her bare fingers and rubs it with her thumb. An expert collector would *never* handle metal objects with their bare hands like this, as the acid on the fingers will corrode the metal. Cleaning the coin afterwards is also not an option, as this presents an even higher damage risk. See http://www.stujoe.com/content/view/30/34/ for more details.
Factual error: During the heist preparation scene, Riley enters the National Archives Metro station to record surveillance camera footage. Surveillance camera feeds for the National Archives would never be accessible within a Metro station due to both security concerns and the fact that the feeds are not needed outside of the National Archives building.
Factual error: The security to get into Independence Hall is very strict, since the terrorist attacks on September 11, 2001. Security would not have allowed Ben to keep his pocket knife when he entered it. This should not be confused with his disguising as a janitor, as this happened at a different location (National Archives) earlier in the film.
Factual error: To reveal the invisible ink on the back of the Declaration, Ben and Dr. Chase use pure lemon juice before warming the surface. This is best seen when Chase first test it out on the corner, where the Mason symbol is placed. Lemon juice is in fact also used as invisible ink (that you have to heat to make visible), and this procedure would have ruined anything written on the back of the document.
Factual error: In the scene when Ben, Abigail and Riley are on the tower of Independence Hall, they look at the shadow marking the secret place where the glasses are hidden. It is 3:20. The shadow of the cross is in the second third of the pillar. When Ian is on the tower the shadow has already moved to the top of the wall. As the others have left Independence Hall at 3:28 the shadow must have traveled the distance in about 4 minutes. This is far too quickly.
Factual error: When Ben and Abigail and Riley separate at Independence park Abigail and Riley could not possibly have exited the park and run right into the Reading Terminal Market. Independence park (where the liberty bell is housed) is between 5th and 7th and Walnut Streets, and Reading Terminal Market (where Abigail hides from the bald man) is at 12th and Arch street. At least 15 blocks apart.
Factual error: In the scene under the Trinity Church in New York, on the wall are two metal support beams in the shape of an X. There are bolts and washers securing the beams. Judging by the elevators that are operated by pulleys, there should be wood with square nails in the time period which the underground passage was built. Seeing the total state of disrepair in the underground elevator shaft, it is extremely unlikely that any updates/repairs were made significantly later than the time it was originally built.
Factual error: On the back of the Declaration of Independence when the Masonic square and compass are revealed, there is a "G" in the center. This "G" was not used until the period of the Civil War. Confederate Masons refused to use the "G" as they considered it a Yankee trick. Even today the Grand Lodge of England does not use the "G." For these reasons it would be unlikely that the Masonic symbol displayed on the Declaration would have included a "G."
Factual error: When Ben, Riley, and Abigail are in Independence Hall in Philadelphia and roll out the Declaration of Independence to inspect with Ben Franklin's special "ocular device" that Ben had just found, Ben pauses to take in the moment. When asked what was the matter, Ben says "It's just that...the last time this was here (in Independence Hall)...It was being signed." However, according to archives.gov, "In 1876 the Declaration traveled to Philadelphia, where it was on exhibit for the Centennial National Exposition from May to October. Philadelphia's Mayor William S. Stokley was entrusted by President Ulysses S. Grant with temporary custody of the Declaration. The Public Ledger for May 8, 1876, noted that it was in Independence Hall "framed and glazed for protection, and... Deposited in a fireproof safe especially designed for both preservation and convenient display." Sorry Ben.