When Jimmy begins to write a note to Ruth, he is writing along the narrower side of the page (portrait orientation). When Ruth removes the note from the door, it is shown written in landscape orientation.
The burnt remains of the letters retrieved from the fireplace were completely blackened consisting of ashes only. The reconstructed letters in the photographs shown in court are mostly intact with only the edges burned away.
After the truck crashes into the car, Jonson is standing next to Walter with his left over his eyes. In the close-up, though, Jonson's hands are at his side.
When Ruth is holding and reading the note Jimmy left for her, she is wearing a dark nail polish. A few minutes later when she is squatting next to her dead husband, her nails are very light colored and of a different shape.
The truck driver, Harry Jonson, told Mason and Drake the accident was due to brake failure caused by a cut brake line - then mentioned the truck has air brakes. Air brakes work in reverse of hydraulic brakes; a cut air line will not allow the brakes to release. That truck should not have been rolling, with a broken line.
Lt. Tragg says he has an arrest warrant for suspicion of murder. Arrest warrants are not issued for suspicion of crimes, the warrant would be for murder, and only if there was enough evidence to believe a conviction was likely.
When Burger introduces two photo blow-ups of the partially damaged love letters for evidence, the two are quickly shown, but on closer inspection, both are the exact same picture.
Jonson's truck crashed into Walden's car hard enough to seriously injure Walden, but neither the car nor the truck show any damage.
When Walden's car is found in the gully, it does not show significant damage for a rollover accident off of the road above, including where it was struck by the moving van in the previous crash. Not even the windshield is broken. it appears to simply have been placed in position and turned onto its side.
While Jimmy is talking on the phone with Ruth, you can see the shadow of the microphone across the front of his shirt.
Upon discovering the embezzled furs, Lt. Tragg tells Sgt. Brice, "Get Robbery Detail." This fur theft, like most others, occurred without the threat of violence, so Tragg should have referred the matter to a detail that handled property crimes.