Plot hole: People who do not have their souls retrieved, before they are killed, will suffer the effects of the death on their soul, eg. the autopsied man has scars and cuts on his soul. So how come the woman who was crushed by a piano (whose soul was only ever retrieved afterwards) is unharmed in soul form?
Plot hole: When George gets into the lift at her office, her reflection is very obvious on the sliding doors, but we were told back in the pilot that Reapers have a different visage to the outside world that shows up in reflections, on camera etc.
Chosen answer: The Song is Callled "Boom Boom Ba" and is by the band Metisse. it plays at certain points during the series. Mainly when George is looking over Reggie or in Reaping Havoc where it plays whilst shes showing her scrapbook "Mysterious and Reassuring" which is what she thought Betty was.