Some chests/containers in the module are destructable. Bashing a chest deals damage to the chest. Before EE, dealing enough damage to the chest would destroy the chest and leave remains behind that could be looted to collect the contents of the chest.
This is sometimes true in EE. However, I have noticed that if you succeed a bash check at the same time as destroying the chest, no remains spawn. This also occasionally happens when destroying a chest without succeeding a check but this is a rarer occurrence.