At a guess I would say that the "flashing pink" (actually red) rail nodes are improperly formed procedural track junctions. If the junction does not have enough space to properly form (e.g. to add the check rails, etc) or has a curve radius that is impossibly small, or one or two other factors, then the normally white or yellow spline point at the junction will flash red. That has been my experience and it has, at the very least, taught me to take greater care when adding track junctions.
