There was a part of the funeral rite early on in Roman history that probably existed to make sure that dead people were actually dead, called "Conclamatio". It means "shouting/crying together" and that's pretty much what it was: The dead person's eyes would be closed and then the gathered family would loudly call the name of the deceased multiple times. Only after that would you prepare embalming, lying-in-state, etc.
In some cases, this "Conclamatio" would be done by a "Pollincor" or "body-washer" who, as the name suggests, also washes the body of the deceased thorougly and (hopefully) only procedes with his work if he has no doubt that the dead person is, in fact, dead.
Whether this "Conclamatio" was primarily used as a way to prevent you from being buried alive or if it was just an accepted part of the extensive funeral rituals is unclear, but sometimes suggested by both ancient and modern historians.
Accidentally burying someone alive still probably happened, but I was not able to find a particularly well-documented example for it.