When Maura asks Joe Harris why he used her to provoke Jane, she wonders why he did not use Jane's sisters instead. But the only siblings of Jane that have been mentioned so far in the show is 2 brothers. Correction: This was done to show that Joe Harris didn't know anything about Jane and wasn't the mastermind.
At approx. 39 minutes, Joe Harris has just knocked Maura out again, and the camera is on her. Just then, a female-sounding cough is heard, but off camera.