I was installing my new bumper plugs the other day and when I went to push the first one in the threaded insert fell in. I hardly put any pressure on it, which surprised me.
I didn't have any problem on my '04 when I did this.

So anyway, does this require the removal of the bumper to get the insert back on? I was thinking I could remove the plates up top to get access somehow but after looking at the Honda parts illustration it doesn't look like it would be that simple.

 

I think the foam absorber is right there behind the holes so you have to remove the bumper. I removed mine to fix it when I had the same thing happen. There are two tiny pegs that stick out of the bumper to hold the insert in place which are easily broken if you bump into something with the license plate mount. I used some bumper repair epoxy to reattach the insert.

 

Thanks Oats, I've been researching bumper removal and have found some useful information. I'm sure I'll have to secure the nut insert somehow.

 

I learned that lesson, now I apply some JB Weld to the insert the day before. I threaded in a screw to keep the bracket from dropping down, then applied the JB Weld with a toothpick. The next day I was able to pop In the bumper plugs.

 

I lost a threaded insert and was able to retrieve it by disconnecting part of the top of the bumper cover, pulling it forward and reaching in. YMMV depending on where your inserts ended up. It would probably be easier just to remove the entire cover.

 

Remove the bumper would be the way to retrieve the insert, or a couple of drops of clear silicone seal on the plugs and your done.