Blond real estate agent?

I saw this yesterday (for free, thank God!) One incident that I thought was going was going to be resolved was the blond real estate agent. While they were discussing what to do with the dead blond woman (yes she was really alive) the bell/intercom rang. Its suddenness was well played for shock value. One of the guys related that it was a real estate estate who wanted to show The Loft. But no one put it up for sale. The womans voice said Sara Deakins put it up for sale, she was the about to be dead nlond girl on the bed . One of the guys replied it was no for sale and looked out the window to see a woman resembling Ann Morris character (to the audience) walk away from the intercom.So did Ann Morris know about the incident. It turned out she had a key to the Loft later. Was is a huge gaping plot hole??