When Rufus Buckley examines Deputy Looney in court, he addresses him as "Detective" instead of "Deputy".
The Klan leader tells Freddie Lee Cobb that if he brings five friends who share similar ideals, they can all be part of the Klan. However, during their introduction to the group, Cobb only brings three guys.
When Jake (McConaughey) finds the bomb in the briefcase, he pulls the clock timer off and throws it. Then it explodes. But when the shot goes back to the briefcase, the dynamite is still there.
As the verdict is announced, the nurse in Roark's room sees a shot of Jake, Lucien and Harry Rex on TV. This event is outside the courthouse and doesn't occur in the movie for another full minute.
When the Klansman rolls around, trying to put out the fire, the daytime shot suddenly switches to night.
At the diner, Ellen's bra strap is showing in a close-up, but it's under her shirt in the wide shot.
Lucien enters the courtroom while Jake is giving his final summation. He stands at the back, disappears, then returns at the end of the summation.
When Rufus Buckley is shown from afar, just before questioning Cora Mae Cobb, she is not on the stand. In the next shot, she is on the stand.
When a fight breaks out in front of the courthouse, an aerial shot shows Ozzie and the officers running to the street. In the next shot, they are running full speed down the sidewalk.
Early in the film, Carla is doing something on the floor (painting?) and is shiny with sweat. Her face is absolutely dry when she gets up, but her body and neck are shiny.
While Carl Lee is being exam'd & cross exam'd, the reflection of the sun off of people's sweaty heads changes 180-degrees between (most) close-ups of the jury Vs. the rest of the courtroom.
During the picnic at the end of the movie, a black youth with a dark scarf on his head stands in the yard. In the next aerial shot of the picnic, the same youth is coming down the front porch steps.
When Jake goes to the judge's house to discuss "Change of Venue" before the trial; the shadows on the brick wall behind the judge change 3 times in only two(?) minutes.
During the sniper shooting on the courthouse steps: Ellen (Bullock's character) switches from one side of the steps to the other between shots after she has first turned around to get back into the building.
At the airport, when Jake sends his family away, a UPS plane can be seen in the background. At that airport, the cargo terminals are south of the passenger terminals, and cannot be seen from the north side of the terminal (where the outside scene was set).
The movie shows Carl Lee being found not guilty by reason of insanity and ends with him fully free and able to attend the same event as Jake. That is not how that law actually would be carried out. While Carl Lee wouldn't face jail time, he would certainly face either a term of commitment at a mental facility or supervised probation, and would not be able to resume a normal life as quickly as is shown here.
When Ellen and Jake officially meet for the first time outside of Jake's office building, Jake asks Ellen what brings her to Canton. Ellen replies that it was Carl Lee Hailey that brought her to town. But in fact Ellen came to town for the arraignment of the rapist Billy Ray Cobb and James Louis Willard, before she would have known who Carl Lee Hailey was.
If Jake is having trouble paying rent in the office with his practice and is having trouble paying his secretary, where is the money coming from to remodel his house?
When Jake calls Max after the fire, Max tries to run past him, apparently toward the off-screen dog wrangler.
When Rufus and his team dramatically enter the courtroom, the inner doors fly open as if they're walking at speed into the room. But the outer doors just behind them are fully closed, indicating they were waiting in that chamber for the "action" cue.
After the Klan hang Roark to the tree, Cobb takes off his white mask and speaks to her. He leaves the scene without picking it back up.
At the end of the movie, when the doors to the courthouse open, a child runs out and first announces "Guilty", before screaming over and over "He's innocent!"