I'm not sure how much this really counts as a movie but I watched a 1961 US Army training film about how to conduct a basic autopsy.

It was full of graphic disgustingness and showed a real autopsy from start to finish.


EDIT: To say that if anyone would like to see this also they should just PM me and ask about it. I know some of you are into gore films (Guinea Pig) and this real autopsy video beats all as for as gore.