Yes, initially the Nazis were confident that since they were going to win, they didn't need to hide the evidence of their crimes by actually disposing of the bodies. This was known as "Action 1005" which was designed to remove evidence of Nazi mass murder in many places, by the building of cremation ovens to get rid of future bodies and the burning of bodies that had been buried in mass graves. Corpses would be dug up by Jewish workers (who would later be killed so they couldn't speak about what happened) put on huge pyres and burned, and then finally the Jewish workers would take the bones grind them and scatter the ashes. This happened in Goeth's camp as depicted in the film.

It didn't just happen in camps though, the Nazis did this in occupied territories where massacres had been committed. In Poland and Yugoslavia these Jewish workers were put to work removing evidence of the Nazi crimes. Also several camps like Chelmo and Treblinka were completely destroyed, in the case of Treblinka, it was destroyed after some inmates managed to escape and thus the Nazis removed it for fear of word spreading about what was truly going on in these special camps. They even put up farmhouses on a former camp location to further cover up the existence of their crimes. There was also orders from Himmler to strictly avoid speaking about the existence of the camps.

The Germans took great pains to cover up evidence of their mass murder. In response to the question yes they exhumed a huge number of corpses in order to burn them. This actually highlights one of the more chilling aspects of the Holocaust, the trial and error nature of extermination and removal of bodies techniques. Once the Germans found something that worked they would begin adopting the same technique in other camps. In the case of removing bodies they originally had trouble burning bodies because they would not burn for long enough. This led to the Germans layering the bodies between stacks of railroad ties. The ties would burn long enough and hot enough to burn the bodies to ash. The brutally efficient, essentially industrial, way that death camps like Treblinka and Belzec dealt with the process of murdering people and removing their bodies is what truly sets the Holocaust apart from other horrific instances of genocide.

The Germans also took further steps to conceal evidence of the death camps. They often plowed of the areas of the camps and planted trees and lupins. In the case of Belzec a fake farm was erected on the site of the camp and a Ukrainian SS soldier was assigned to live there with his family in order to guard the site.