Mary Surratt's house is now a museum in what was then Surrattsville, Maryland. The U.S. Post Office renamed the town Robeysville, due to the notoriety of the Surratt name. In 1879, Robeysville was renamed Clinton.
Robert Redford insisted that the actors stay in costume as much as possible so that the clothes would start to feel natural to them. Most of the actors complained at some point because the filming locations were unbearably hot.
The look of the film was influenced by early photographs of the period, many of which tried to introduce elements of color over sepia. Director of photography Newton Thomas Sigel attempted to emulate that look while restricting the use of bright, artificial light.
Toby Kebbell plays John Wilkes Booth, the man who assassinated Abraham Lincoln. He previously played Pausanias, who assassinated Philip II of Macedon (father of Alexander the Great) in Alexander (2004).
Shots of the audience watching the play were filmed months after shots of the play. The audience's reactions were shot on the same stage as the court room. The extras watched the play on a small TV monitor while Robert Redford directed them. The double who stood in for Booth split his pants when he fell from the "box window", and the footage of the extras laughing was the result.