The syringe used to administer the cyanide was said by the doctor to be an insulin syringe. It is actually a tuberculin syringe. Insulin syringes are measured in units and they are orange at the base of the needle. Tuberculin syringes measure cc's and are brown/tan at the base of the needle which is the one on the floor picked up by Jessica.
When Jessica is comparing Carrie's handwritten letter to her Last Will and Testament, the supposed "will" is actually what appears to be a page from a transcript of one of Jessica's books. The "will" starts with "It was a dark and stormy night in Cabot Cove. I sat in my favorite rocker contemplating the evenings happenings with anxiety and regret."