"My favorite song is playing on the radio."
Translation:По радио играет моя любимая песня.
Since word order is not strict in Russian, 'моя любимая песня играет по радио' should be acceptable as well.
Actually, this just does not sound natural in Russian. I am not sure a native speaker would say that. Maybe it was OK about 70 years ago because it sounds quite old-fashioned (on the other hand, I am not old enough to confirm it).
Removed the sentence.