15.4" Retina MacBook Pro (Mid 2012): Broken metal pieces from connector on the motherboard
If it is the connector for the part you have circled in red in the left picture on the bottom row, that is a microphone assembly, containing two microphones. So if i understand you correctly in that the connector where the flat cable contact for this assembly slides into, on the motherboard, partially broke, you will now probably not get any mic input registered on your Mac, although I am uncertain if this model also has a mic in the lid next to the camera.