  Using polarization selective spontaneous Raman scattering, we have
investigated the 5$d$ transition metal compound K$_2$ReCl$_6$ which displays a
series of structural phase transitions. We observe a violation of the Raman
selection rules in the cubic high temperature phase as well as a low-energy
scattering continuum persistent throughout the investigated temperature range
from 300 down to 5 K. The continuum couples to one of the phonon modes at
temperatures above the lowest structural phase transition at 76 K. We propose a
common origin of these observations caused by local fluctuations in the
orientation of the ReCl$_6$ octahedra which locally break the long-range cubic
symmetry. Consistent results from the related non-magnetic compound
K$_2$SnCl$_6$ support this interpretation.
