Check out this short record, from the composing of BTQ.

You can see that there's multiple layers in many places, which suppose to "fix" some bugs/add some effects.

On the start - you can see that i forgot to "unhide" the table in the scene - so i rendered aroud thousand frames without the table below Interrogator. It's not actually hidden, cause you can see the shadow - it's just not visible for the camera (but visible for shadows/reflections). I was using that for the "bottom cam", but forgot to disable that setting.
To fix that - i have to re-render a "region" part of the image, with the table visible.

Plus, couple of other random fixes/blends.
Check it out:

VIDEO