I'm assuming you are thinking of using Trello as a bug tracking app? We purposefully did not design Trello to be used that way, even though a lot of people do, so it might fall down when you go that route. It is not a replacement for a bug tracking application. There are plenty of those out there (FogBugz, Jira, Pivotal) and there are even kanban type programs like Trello for software development (AgileZen, LeanKit, Sprintly).
Trello is designed for a high level overview of a project. So if you start to get too many items on your board, either it's not the right tool for what you are trying to do, or you need to think more about what you are adding to Trello. For example, you could use Excel to take notes, or make a todo list, but it's not the right tool for that. Trello really shines when you are using it for group collaboration and either focusing on a high level (and leaving the details to something else) or only focusing on the very top level important details.
I know a lot of companies that use Trello in tandem with tracking apps. There's even a nice bookmarklet that integrates with a bunch of them (FogBugz, Jira, Github, Saleforce) so you can hit one button and turn your case into a card in Trello. See https://github.com/danlec/Trello-Bookmarklet But don't make the mistake of trying to duplicate what those programs do in Trello.