Cora Smith: It's too bad Nick took the car.
Frank Chambers: Even if it was here we couldn't take it, unless we'd want to spend the night in jail. Stealing a man's wife, that's nothing, but stealing a man's car, that's larceny.
When Frank, the DA and the policeman are discussing the accident, the policeman notices the electrocuted cat and it is shown next to the ladder. In the subsequent wide shot the cat is lying between the beams of the ladder.