For the last rallycross, I was too busy getting my tow vehicle ready (replacing the rear struts and internals of the DEF tank) that I didn't take the time to get everything checked on the Frog.
The rear struts are modified VW Golf front struts:
6 months to live build thread
The bottom bracket on the left strut was not tightened enough. It rotated and the strut slipped down. No serious damage, but I only got one run and had to quit for the day.
I was going to swap the stock rear suspension from the Parts Car, but I'm not going to have enough time before the next race day. The Parts Car still runs great and has functional air conditioning. I'm going to put a spoiler and some good tires on it and run it one more time.