Corrected entry: At the end of Saw, Doctor Gordon cut his foot off clean. When he enters the bathroom in Saw 3D, the foot now has bone poking out. It couldn't be because of decay because the rest of the foot still has flesh on it.
erikvduyn
3rd Nov 2010
Correction: It is decay- if you look closely, the flesh and "meat" has shriveled, leaving the bone exposed.