OK, think I got it figured out. I went back into the garage and found a plastic piece sitting near where we found the spring. It appears that it snaps into the cap of the filter housing and the spring we found goes between the cap and the plastic piece. Now the filter will snap into the cap like it is supposed to. He must have twisted or something to have the other parts come out while trying to pull the filter off the cap.
Could someone add a warning about this to the FAQ on changing the oil?