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.
Picture added by Ronnie Bischof