When the turtles are training in the junkyard, they spot Krang, Shredder and his henchmen which are obviously cardboard. Leonardo then slices Shredder in half. This wouldn't be allowed in an actual confrontation due to censorship, hence the foot soldiers being robots instead of human. Human foot soldiers can't be attacked with sharp weapons.
Vernon brags about how he has the biggest story of the century but he never removed the lens cap.