What kind of mistakes do publishers make during the development process?

The publisher’s producer needs to be good at spotting red flags and should have a good working relationship with the developer so she can help them work through issues in a productive way. Publishers often find out too late that there’s an issue that can no longer be addressed. A good publisher keeps on top of that stuff, as long as the developer is being responsible and open with them. A bad publisher won’t take notice of problems until it’s too late. But again, the publisher really needs to work to establish trust with the developer (and vice versa) or none of this works.