Sweepers found some debris near the runway characterised "as metal" but it doesn't seem certain they were 100% certain it was from the accident flight
"Following the accident, the United States Air Force recovered a segment of white hydraulic (return) tubing from Runway 03 in the area of Taxiway C (Charlie). Following an examination of the tubing, Boeing indicated that the tube was part of Hydraulic System #2 and was installed in the area aft of the aft pressure bulkhead."
As the runway was swept after the departure of every heavy, the debris couldn't have come from anything other than the accident flight.