Incorrect handling of 404?

[eluser]AeroCross[/eluser]
Good morning, fellas.

I've been noticing a strange behavior in the way that CodeIgniter handles the 404 error (since it's kind of a "special" error).

Suppose I have 2 controllers: login (with methods index, create and validate) and notifications (with methods index and missing). In the routes.php, my 404_override is "notifications/missing". If I enter in the url http://example.com/loginssads/someurl (a controller that doesn't exists), the proper controller and method loads.

But, if I enter http://example.com/login/adsadsads (a controller that does exists, but a method that doesn't) then the errors/error_404.php template loads, NOT my custom 404 page.

Is this a bug? I think that the 404_override is missing something.

Also, there's no documentation about the variables available inside the errors folder (like $heading), not what can I use (I don't know if that's a view, or something).

Any help about this issue is greatly appreciated.