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.
Audio problem: Each time George mentions Millie's older brother Luke, the movements of her mouth don't match what's being said. It appears that the name was changed and then dubbed afterwards.
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.