Gregory Peck's 9 minute summation speech was nailed in one take.
Robert Mulligan's way of handling his child actors was to let them play together while keeping the cameras as unobtrusive as possible.
William Windom's movie debut.
Brock Peters delivered Gregory Peck's eulogy on the day of his funeral and burial, June 16, 2003. Peck defended Peters in To Kill a Mockingbird.
Brock Peters started to cry while shooting the testifying scene, without rehearsing it this way, and Gregory Peck said that he had to look past him, instead of looking him in the eye, without choking up himself.
Ruth White would spend 4 hours getting into old age make-up, only for most of her scenes to end up cut from the film as they tended to slow it up.
Alice Ghostley's movie debut.
Truman Capote, who grew up with Harper Lee, also knew the inspiration for "Boo" Radley, and had planned to base a character on him in one of his short stories. After seeing how well the character was realized in Lee's novel, however, he decided against it.
Horton Foote was initially reluctant to adapt the novel into a screenplay as he felt that he would be unable to do it justice.
Mary Badham (Scout) and Gregory Peck (Atticus) became close during filming and kept in contact for the rest of his life. He always called her Scout.
Mary Badham became the youngest girl to receive an Oscar nomination, ironically losing the award to another child actress, Patty Duke in The Miracle Worker.
Mary Badham messed up nearly every take in which the family was eating at the table. Phillip Alford didn't like eating the same meal dozens of times, so in one of the takes of the scene in which he rolls Badham in the tire, he aimed it at an equipment truck in an attempt to hurt her.
Phillip Alford told his mother that he did not want to go to the auditions for the part of Jem Finch but when his mother told him he would miss half a day of school, he immediately decided to go to them.
Robert Duvall stayed out of the sun for six weeks and dyed his hair blond for the role of Boo Radley who, according to the story, spent much of his life as a recluse. The character of Arthur "Boo" Radley is based in part on Harper Lee's recollection of Alfred "Son" Bouleware, who lived with his parents in a dilapidated, mostly boarded-up house just a few doors away from the Lee home. He was kept secluded in the house by his father, following a vandalism incident in which young Alfred was involved. Described in the book and in the movie as leaving the house only at night because the sun hurt his eyes, this would indicate that Boo Radley was a person of Albinism (lack of pigment in the skin, in the hair, and in the irises of the eyes.)
Robert Duvall's first movie.
A car is not shown driving down one of the streets until 42 minutes into the movie.
According to the comics, this is Clark Kent's (aka Superman) favorite movie.
After being offered the part of Atticus Finch, Gregory Peck read Harper Lee's novel in one sitting and called Robert Mulligan immediately after to say that he would play the part.
Although Gregory Peck's inspirational performance as Atticus Finch turned out to be a perfect highlight to his long career, Rock Hudson was actually the studio's first choice for the role. James Stewart was also offered the part, but told the producers he believed the script was "too liberal", and feared the film would be controversial.
Art directors Alexander Golitzen and Henry Bumstead had an entire reconstruction of the fictional town of Maycomb, Alabama, built on the Universal backlot at a cost of $225,000. The set contained more than 30 buildings. It would have cost at least $100,000 more had Golitzen and Bumstead not learned of some Southern-style housing about to be demolished to make way for a new Los Angeles freeway. They bought a dozen of them and had them brought to the studio. Such efforts resulted in the two winning the Oscar for Best Art Direction the following year.