The point is that, individually, there are precedents for each part of the story, not that they have all been tied together before. One of the graphics near the end illustrates this.
The 23 deaths part is a huge stretch though. There's been a few noted injuries at such mobs when turned riot but I can't even find an example of a single death from a flash mob type gathering.
There have definitely been riots however which have lead to deaths. Flash Mob -> Riot has happened, Riot --> Deaths have happened. Flash Mob -> Riot -> Deaths not yet.
Sure, it's definitely a stretch. He was a bit hyperbolic (as with the getting lost due to having no 3G bit). I can't think of any riot with more than a handful of deaths in a western country over the last 20 years (?)
I'd say the "getting lost due to having no 3G bit" was one of the /least/ hyperbolic things - I can imagine that happening to me pretty easily nowadays.
