  Taking the principles of quantum mechanics as they stand and applying them to
gravity, leads to the conclusion that one might be able to generate
superpositions of spacetimes, at least formally. We analyze such a possibility
from an analogue gravity perspective. We present an analogue toy model
consisting of a Bose-Einstein condensate in a double-well potential and
identify the states that could potentially be interpreted as superposition of
effective spacetimes. These states are unstable and the source of instability
from a microscopic point of view can be related to the absence of a
well-defined causal structure in the effective geometric description. We
explore the consequences of these instabilities and argue that they resonate
with Penrose's ideas about the decay that superpositions of states with
sufficiently different gravitational fields associated should experience.
