Noun for "things that could be improved"

Solution 1:

An imperfection. But really, everything can be improved (except perhaps God) so the question is really moot.

Solution 2:

I don't know how I missed the word "improvement".

a change or addition by which a thing is improved. (Dictionary.com)

This was originally mentioned in a comment by Dan Bron.

Solution 3:

The closest thing that comes to my mind is "deficiencies".

To use your examples, reworded:

I've found some deficiencies in your project.

and

There are a bunch of deficiencies you should correct.

This doesn't exactly mean things that can be improved, more like things that are lacking. But the implication is that the things that are lacking should be added / added to / corrected, which seems quite close.