I jumpseated on a Spirit A320. The gate was hectic and all of a sudden the FO comes out of the jetbridge telling the gate agent she’d given him the release from the day before. They let me on, with about 20 open seats. I elect for the jumpseat because, Spirit. Once I’m in there I learn the plane had been overfueled by 10,000 pounds because of the wrong release. What?? So they send the fueler back to empty the truck so he can come defuel the Airbus. On his way back, he flips the fuel truck, spills fuel all over the ramp in Atlanta, and has to go to the hospital. Awaiting takeoff, the captain jetblasts a Delta 737 behind us with about 88% N2 to burn fuel. We proceed to fly ATL-ORD AT 17,000 feet, drop the gear over the lake for the downwind, and land AT MLW. Craziness.