Seriously, right. When they were making Spartacus, the battle between the slaves and the Romans specifically, to make it look like dudes were getting chopped in half they had dwarfs with fake torsos. The dwarf would be sitting underneath the torso and the sword would come along and remove enough of the fake torso so that it looked like the guy was being hewn in two.
I know this because the trivia section on IMDB is like, one of my best friends.