Corrected entry: When Rusty is first charged with the murder, the police obtain a search warrant for his house and they do what appears to be a thorough search. Near the end of the movie, it is revealed that the murder weapon was a roofing hatchet/hammer, kept in a tool crib, stored in the basement of Rusty's house. Given that the police knew the nature of the murder weapon, it is inconceivable that the basement of the house would not have been searched for such a weapon. When Barbara confesses to the murder, we learn how detailed and thorough her plot was. Given her attention to detail, it is hard to understand why she would have not washed the blood and hair from the hatchet/hammer before it was returned to the tool crib.
Corrected entry: When Carolyn Polhemus is questioning a young witness on the stand, she commits several legal errors that would certainly have led to objections from the defense. For example, she asks, "Did someone put your head in the vise?" That's called a leading question, and is generally not allowed during direct examination, even if the witness is a child. Then when the child doesn't answer, she asks "What did you say when someone put your head in the vise?" You can't legally ask the follow-up question when the first question has not been answered. Even if the defense lawyer allowed the leading question, which is unlikely, he would certainly have objected to the follow-up question.
Corrected entry: Harrison Ford takes the ferry home across the Detroit River - which is doubly problematic: There is no ferry service across the Detroit River, and it would mean that he lived in Canada, which is across from the Detroit River. City employees have to reside in the city, and county and state employees have to live in the state.