Continuity mistake: When Ian looks down to the shadow cast by the "House of Pass and Stow", the shadow isn't anywhere near to where it was when Ben looked down, although not very much time could have elapsed.
Continuity mistake: In the scene where the group are revealing the cipher on the back of the Declaration of Independence, in a wide shot, we can see glass on the corners of the Declaration to keep it in place. When Abigail rubs the Q tip on the right corner, the glass is gone.
Answer: "The Secret Lies With Charlotte" ~ Charles Carrol of "Charleston".