  Flat Space Cosmology (FSC) spacetimes are exact solutions of 3D gravity
theories. In this work, we study phase transition between FSC spacetimes and
Hot Flat Spacetimes (HFS) in general minimal massive gravity and exotic general
massive gravity. We show that similar to topological massive gravity the
tunneling occurs between two spacetimes by comparing their free energies. We
also obtain the corrections to the Bekenstein-Hawking entropy, and its effect
on the phase transition is studied.
