The legless zombie wasn’t a result of CGI a la Lt Dan in Forrest Gump, but rather a legless stuntman gussied up to be a zombie. The ‘how they did it’ feature on some of the zombies is well worth the purchase price of the DVD.
I remember watching “The Best Years of Our Lives” with my mother, and she wondered how they did the “effect” of the sailor who’d had his hands blown off. Same thing. The young man, Harold Russell, was a sailor who’s hands were blown off in an accidental explosion.