Let $mathcal{M}$ be a von Neumann algebra, and let $0<p,qleinfty$. Then the space $Hom_mathcal{M}(L^p(mathcal{M}),L^q(mathcal{M}))$ of all right $mathcal{M}$-module homomorphisms from $L^p(mathcal{M})$ to $L^q(mathcal{M})$ is a reflexive subspace of the space of all continuous linear maps from $L^p(mathcal{M})$ to $L^q(mathcal{M})$. Further, the space $Hom_mathcal{M}(L^p(mathcal{M}),L^q(mathcal{M}))$ is hyperreflexive in each of the following cases: (i) $1le q<pleinfty$; (ii) $1le p,qleinfty$ and $mathcal{M}$ is injective, in which case the hyperreflexivity constant is at most $8$.