A common objection to faster-than-light communications is that it would permit sending info to the past, thus putting effects before causes. Let's look at that. On my perfectly ordinary radio, I can send a dit from Florida to Australia at 0000 UTC. The Aussie will get it at 0000 plus 72 milliseconds.
Now if I were a whiz-bang physicist (I'm not), I could invent a system that had no delay at all. Send at 0000, receive at 0000. But still, nothing in the world would make that dit show up at 2359. Effects remain after causes.