When Greg is trying out his father's chair, the letter opener that would later become the murder weapon is visible on the desk in front of him. When the viewpoint changes to that of the person outside the window, the letter opener is no longer present.
It is doubtful that, just two hours after taking two sleeping pills, Sue Ellen would have awakened and been alert enough to drive.
After Lt Tragg removes the shoes from Greg's car, in the long shot DeForest Kelley (Peter Thorpe) is very obviously standing on his marks. They are very clearly on the ground around his shoes.
At the very start of the courtroom scene, when Mason is questioning Lt. Tragg, he uses the term 'burglared', which is not a word. The actual word he should have used is either 'burgled' or 'burglarized'.
When Perry agreed to defend Sue Ellen, he failed to inform Walter that in defending her he might cause harm to Walter, as he has done with other clients in other cases. Although Walter had already given his consent, Perry had an obligation to ensure that it was informed consent.