Multiple references to the same object
This smells bad to me:
I have a data object. That data object is referenced by a class field in the parent container, and a class field in some of its children.
ALSO, the children have the data object referenced in a superclass field, as well as a field in the child class (down cast type).
So, I have multiple references to the same data object in 1) the containment heirarchy; 2) the class heirarchy.
This seems like asking for trouble, as someone will miss updating one of these references someday. My natural inclination is to use a hashmap to tie one data reference to muliple class instances, like: <data>::<list of referrers>, but that doesn't really work for finding an instance's data object (does work for updating the data instance of all referrers, though).
There must be a simple solution to this, but I'm in a brain fog today.