Middle Mouse Button Zooms out the camera for a quick peek of the map.
Clicking the middle mouse button on a soldier’s picture pulls up the soldier info window along with zooming the camera out; however, the camera does not return to standard view. If you continue to click the middle mouse button on the soldier icon, the camera will continue to zoom out until, eventually, you see nothing. The game still plays fine; the camera just will not return to normal. Discovered this by accident, but it seems to happen in any mission.