Everyone else has pretty much covered what I would have added, so I won't go there... but Deanna mentioned going downhills in a bunch...

Etiquette - especially racing etiquette - suggests fast down-hilling should be done single file, never in a bunch.

It sounds like that is what was happening with slower down-hillers hugging the side enabling faster riders to pass and essentially keeping to one line.

Going downhill in a bunch - especially if there are corners, can be particularly tricky and sometimes downright dangerous.