Is It Illegal To Have A Broken Side-View Mirror?

This really depends on where you live - some countries (or states) are more lenient about this than others.

Most police officers will be quite understanding, as they know that you can't really get it repaired without driving it to the place where it will be repaired! As long as you're apologetic and polite, you should be fine.

What Can I Do If I Get Pulled Over?
Usually, the police won't take any legal action if you're driving with a broken side-view mirror.

They'll probably just tell you to get it fixed - it might help if you tell them that your mirror got smashed that day, even if it happened a week ago.

Regardless of whether or not it's legal to drive without a side-mirror, it's still dangerous - ideally, you want to get it repaired as soon as you can. It won't cost you that much!