Continuity mistake: When Bob Ewell is on the witness stand and Atticus asks him if he ran for a doctor, Atticus is hovering over Ewell and his visible shadow behind Ewell reflects this. When the camera shifts to Atticus, he is a good 10-15 feet away. When the camera returns to Ewell, Atticus' shadow is still there.
Continuity mistake: When the children go to the courthouse and up to the courtroom door, there are two solid doors with covered panels (that do not let light through), with a clear transom window above the doors. However, when the children boost Dill up to see into the courtroom, the doors' top panels are clear windows. (00:20:50)
Continuity mistake: As Jem, Scout and Dill are walking up to the courthouse, they pass a group of men playing checkers. One of the men speaks to Jem and the three stop momentarily. As they respond to the man, two black women as extras pass by them, walking toward the street. The next shot is a continuation of the scene with overlapping dialogue, however, the two black women are nowhere to be seen and there is a white woman with a white hat where the two black women should have been. Jem, Scout and Dill pause on the handrail before running up the steps, and as the camera pans back, all three women are once again walking past the old men.
Continuity mistake: Whenever the porch swing at the Radley house is tousled by the wind, the wind doesn't appear in the following shots at all.