The forthcoming Matthew McConaughey drama “Free State of Jones” lays claim to being the first Hollywood film in decades to depict Reconstruction, the still controversial post-Civil War period that attempted to rebuild the South along racially egalitarian lines.

But the movie, written and directed by Gary Ross, might also lay claim to a more unusual title: the first Hollywood drama to come with footnotes.

The film recounts the true story of Newton Knight (Mr. McConaughey), a Confederate deserter who led a ragtag dissident army from the swamps of Jones County, Miss., and continued to fight for the rights of African-Americans after the Civil War ended.

In advance of the film’s release, on June 24, Mr. Ross, whose credits include “Seabiscuit” and the first installment of “The Hunger Games,” is posting an elaborate website annotating some three dozen topics and scenes from the movie, allowing audiences to click through and evaluate for themselves his historical sources, including many primary documents.