I bet the rear window was intact when they loaded the single pallet in the back and was left open, but slammed shut and broke after beginning the drive.
Problem is what/how do you tow it? Guess take it off the highway, get a few flatbeds and transfer the load. But it would NOT continue.
Pull the idiot over, tell them to remove the pallets, and tell them that they have 15 minutes to figure out how to properly get them out of there before you write them a ticket for littering/dumping.
Give them 15 min to "make it legal" or "safe" then impound it.
when you impound it, be sure to authorize special circumstances on the part of the Tower. especially if your state regulates the towing charges.
A heavy duty rate would apply here. with the size of that civic you could easily stack those pallets on the truck with the car but its going to take some added work on the towers part and he SHOULD by all means be compensated for his efforts.