I can't really tell on my phone what the problem is.
It looks as though on the driver side the nutserts that are molded into the rear bumper have been pulled out and the ones on the passenger side are cracked.
The cheapest way to correct the problem would be to find someone who has a stock rear bumper laying around for little or no money.
This is exactly what happened. Would replacing the nutserts with new ones work? I'll go to ace tomorrow but would I need a slightly bigger nutsert to now fill this holes or would the same size work?