Momentum conservation holds also for quantum mechanics. Energy and momentum conservation are used in studying elementary particle interactions continuously.
In a two body reaction the momenta are correlated, but unknown before measurement. After measuring the momentum of one of the particles, if the masses are known, one knows the momentum of the one that was not measured/observed using momentum conservation.
A prime example was the discovery of the neutrino, which was discovered by imposing energy and momentum conservation on the reaction. Within the accuracies of the experiments the neutrino mass was of order zero, though later, neutrino oscillations showed that neutrinos have a small mass, currently given by upper limits.
By the way, "entanglement" is a fancy way of talking of correlations, and is misleading, since there is nothing mysterious about conserving momentum energy and quantum numbers.