Near the end, at the last murder scene, a shell casing is seen on the ground and found. Although it is clearly a .22 rimfire casing, the statement is made that the victim was killed with a .25 automatic, the casings of which contain a groove in the bottom rather than the rim seen on the .22 rimfire.
When the victim's vehicle is found, Catherine asked a guy nearby "can he open it up?" After he has gained access to the vehicle, he proceeds to open the car door with a bare hand. Catherine should not have allowed this, as there could have been fingerprints on the door handle.