Factual error: In the flashback at the beginning of the episode where Maggie remembers the last time she talked to her children. She getting ready to go out for the evening in Seattle (and it's dark outside) while on a video call with her children in England, telling them that it's late and time for them to go to bed. Since Seattle is 8 hours behind London, and it's dark/evening there, her very young children's bed time must be 2am at the earliest.
Plot hole: Every time the nanos stop absorbing electricity (for whatever reason), street lights, radios, everything 'on the grid' immediately starts to come back on. No re-building infrastructure, no restarting turbines, etc., even 15 year old streetlights lying on the ground, in the middle of nowhere.