When the defense lawyer (Larry Gates) pours a glass of water at 1:29:25, the glass is 3/4 full. At 1:29:28 it is about 1/2 full, yet he did not appear to drink any of the water.
After Hank Bell is attacked by the gang in the subway car, the next shot opens with the doctor in the emergency room examining a chest x-ray that is obviously reversed.
When Danny is cross examined by his lawyer on the court he nods with his head as a form to answer a question, which is not the accepted procedure. Since everything that happens on the court is part of a typed record and to make it clear to a future consultation of what's been said during the trial, when someone on the stand answers with a nod, the question must be repeated (either by a lawyer, prosecutor or the judge) and verbally answered by the person on the stand. However, during the sequence no one follows such procedure, neither Danny - who is presented as a bright kid - does that.
During the trial, Bell has Louisa walk over and touch the shoulder of each of the gang members to definitively identify them as the murderers. No court would ever require a witness to touch a defendant.
The gang leader doesn't touch his first beer.
When Hank Bell goes to Zorro's apartment and walks down the narrow hallway, the shadow of a hand-held camera is visible on his torso.
When Cole asks Bell if he wants to prosecute the case against the boys, a moving shadow of the boom microphone is visible on the bookcase in the background, near the top of the frame.
When Hank Bell gets in the car with Lt. Gunderson after visiting Mary Pace he gets on the police radio and says "over" a few times while waiting for a response, then stops using "over" and just keeps the conversation going. Also, he never presses the button on the mic when talking.