We derive energy norm a posteriori error estimates for continuous/discontinuous Galerkin finite element approximations of the Mindlin-Reissner plate model. The finite element method is based on continuous piecewise second degree polynomial approximation for the transverse displacements and the rotated Brezzi-Douglas-Marini approximation,with tangential continuity only,for the rotations. This approximation enjoys optimal convergence, uniformly in the plate thickness. The a posteriori error estimates are residual based and are derived using techniques based on Helmholtz decompositions.