CPU karts flip vertically and spin erratically in mid-air just after level start

I’m using Ryan Laley’s Kart Series to create a racing game. I’ve gone through Part 14, but in the middle of it, when I’d play my level, my CPU karts just started flying into the air in place while standing vertically and rotating erratically on one axis, though this slows down as it falls, all at the invisible starting line. I tried following the rest of the tutorial then going back through it to see if there was something I missed, but nothing stood out. If I missed anything along the line that would contribute to problems later, I don’t know what it was. Just in case this helps, I’ve taken a screenshot of my game window from the editor, blur conveniently right there.