Continuity mistake: At the diner, before Mrs. Duncan comes to confess about murdering her husband, Brennan takes a sip of tea. Her glass at this point is less than half full. When Mrs. Duncan walks in, the same glass is now almost full.
Other mistake: At the start, when Hodgins gives his findings at the scene a fly can be seen crawling over the camera lens. (00:02:00)
Answer: Answering my own question here but, having contacted various people involved in the production of Bones including Kathy Reichs, Hart Hanson, Eric Milligan, and Deirdre Lovegood who portrayed Taffet onscreen I finally have the answer. No-one know how she did it due to her constantly working alone. And she never revealed this information before her death.
Ssiscool ★