Special relativity should be a special case of general relativity, for flat spacetime manifolds. For locally flat manifolds, special relativity should however give approximate results. But even Earth is a non-inertial frame. So that would mean that special relativity can only be observed for small distances on Earth, when observed along the surface? Muon experiment should not be affected by Earth rotation, for example (IMHO). I am asking this because it seems that Michelson-Morley experiment (MMX) should have returned speeds different from c, similar to a Sagnac experiment when observed from the rotating, non-inertial frame. In other words, did MMX work only because distances happened to be short enough?