Actor Allusion: When Abraham goes after the Vampire who killed his mother, the latter announces that it's 'Abraham fucking Lincoln' in much the same way that Andrew Jackson announces that he's 'Andrew fucking Jackson' in Bloody Bloody Andrew Jackson. Benjamin Walker (who plays Lincoln) originated the role of Jackson.
Actually Pretty Funny: On the DVD commentary, the author relates that some of the film's detractors say it is "the worst thing to happen to Abraham Lincoln in the theatre." He's chuckling as he tells this to the audience.
Completely Different Title: Foreign markets have given the film several different titles, including President Lincoln: Vampire Hunter (Russia, Thailand, Taiwan), Lincoln: Vampire Hunter (Hong Kong, South Korea), The Legend of the Vampire Hunter (Italy), and Secret Diary of the Vampire Hunter (Portugal).
I Knew It!: Raise your hand if you didn't know that Henry was a vampire the first time you saw him.