Advice on Changing Pads in a Parking lot

How the hack did that ever happen?
Thats the job of the pad hold down clips, from keeping the pad(s) from moving away from the top of the rotor.
It was about 4 months after I got the car on the road, I hadn't touched the brakes, they worked, no reason to look at em. Basically some previous owner had replaced the pads, driver's side was fine, but the passenger side the pads were upside-down and the clips were nowhere to be found. Miracle that they stayed in as long as they did. I was driving I-5 towards Seattle at like 3pm, and heard what I later realized was the pad hitting the floor pan, which was a concerning enough sound to make me pull over. Realized I didn't have brakes so I used the trans to slow down (and my little brother for the final stop). Brand new calipers and a month of on and off work and she's been fine till now.