Spielberg has been researching for this film for 12 years, down to the correct wallpaper and books in the White House of 1865 and the right ticking noise for Lincoln's watch (Recorded from the actual one!)
Old Shame: Has been an audience reaction during the voting scene; if they're from a state that had congressmen who did not vote yea, a groan can be heard in the theater (unless you're from Connecticut, in which case you'll be mad that the movie shows two House members voting against the amendment when in Real Life all four were in favor of it).
Playing Against Type: Sally Field, who normally nowadays plays sweet, [grand-]motherly types, as controlling, bitter, mentally unstable Mary Todd Lincoln.
While he's certainly played heroic characters before, Daniel Day-Lewis' turn here is generally subtler than some of his more recent work in There Will Be Blood and Gangs of New York.
Reality Subtext: Daniel Day-Lewis and Sally Field had only met in passing prior to this film. Mary's and Lincoln's relationship is fraught, to say the least; however, over the course of filming the two actors quickly came to adore each other.
The great-grandfather of Michael Stanton Kennedy was a newspaperman from the town where his character, Hiram Price, lived. When filming the scene where the 13th Amendment passes, Kennedy started to cry and couldn't explain why until later, when he told Steven Spielberg "We're in this room recreating one of the most important moments in American history... and up there [in the balcony] with the press sat my great-grandfather."