HI; I'M A BIT TIRED OF LOOKING FOR THE TITLE OF AN HORROR MOVIE IN WHICH A DOCTOR (OR SCIENTIST) IS WORKING WITH THE REMNANTS OF AN ANCIENT CORPSE. WATER FROM A CUP OR SIMILAR CONTAINER ACCIDENTALLY SPILLS BESIDES THE CORPSE AND ON CONTACT WITH THE WATER, A FINGER OF THE CORPSE STARTS TO REGENERATE NEW, APPARENTLY, LIVING TISSUES AND THE REGENERATION ADVANCES UPWARDS THAT FINGRER BUT THE DOCTOR OR SCIENTIST SEVERED THAT FINGER. FAR FROM THAT SCENE, THE STRANGE CORPSE IS BEING TRANSPORTED IN A STAGECOACH OR SIMILAR VEHICLE UNDER A STRONG SHOWER/THUNDERSTORM AND, SUDDENLY, THE STAGECOACH WERE GOING SO FAST THAT IT TIPPED OVER. THE CORPSE GETS WET AND AWAKES, CHASING FOR THE DOCTOR (OR SCIENTIST WHO SEVERED HIS (its) FINGERS AND WHEN HE GETS TO HIM, THE "MONSTER" DISMEMBERED ONE OF it's VICTIM'S FINGERS AS AN APPARENT REVENGE.

The movie you are looking for could be "The Creeping Flesh" - a British horror movie from 1973, directed by Freddie Francis and starring Peter Cushing and Christopher Lee.