Although it is not depicted in the show, the real Laura Hart McKinny did testify at the O.J. Simpson trial and established the authenticity of the infamous tapes of ride-alongs and interviews with Mark Fuhrman.
The song "Natural One" by Shearwater plays (non-diagetically) in one scene. Although its presence in the episode isn't necessarily an anachronism because it isn't playing live in the scene, this song was released in 2013, nearly twenty years after the events of the OJ Simpson trial.