Character mistake: When looking at the car near the start, Sherlock says he can tell by the pattern of the bullet holes that the gun was fired in 3 round bursts. But when we saw the attack earlier, the gun fired in bursts of different lengths.
Continuity mistake: When Joan meets with her therapist, the nook behind Joan is brightly lit. The nook goes back and forth from brightly lit to very dark, sometimes in the space of a three-second cut to the therapist.
Answer: I'm the same person who asked this question. I discovered it was Molly Price whom I recognized from Third Watch.
Cathrine R
It should be noted Donna was Jim Fowkes‘ secretary. Donna killed Peter.
Bishop73