As for as anachronism is concerned, even The Bard was guilty,

... of this and many other anachronisms, but playwrights and stage directors etc. are totally unashamed, rightly so. The special problem with most genres of cinema (and TV) is that they claim a much higher degree of realism than they can deliver. And, as the OP and the above posters rightly deplore, music is often treated particularly carelessly, when a fortune is spent on correct buttons for every single uniform, for example.