My two cents

If you are on a group ride, and your riding is in a responsible and at least quasi-legal manner (10 - 15 km/h over the speed limit probably isn't going to be an issue), and someone behind manages to crash on their own AND the other riders stick around, it's unlikely that there are going to be any repercussions for others in the group.

If you are riding like idiots then all bets are off, particularly if it's witnessed by a significant number of members of the general public. (So don't ride like idiots in traffic with everyone else watching ...)