In the court scene when Sideshow Bobs questioning his father, it shoots back at the audience and you can clearly see his father sitting next to his wife.
During the court scene, the hair of the man sitting to the left of Mr. Smithers changes from light to dark brown.
After Bob is put in the police car and has his hair cut, in the next scene with Bob, his hair has grown back.
Bart calls Sideshow Bob a killer. However, Bob has never successfully killed anyone up through this point.