The biggest mistake that people make in these accidents is that they don’t call the police! They are on the highway and they don’t want to clog up traffic further, or they are in a hurry. They just want to brush it off and move on.
But you must call the police! You also need to get the other driver’s insurance and driver’s license information. If you can do it safely, you also need pictures of both cars. When doing this, however, pull off the road as far as you can and never stand between the two cars or between traffic and the cars. Even if it’s cold and miserable, you must get out of way.
Finally, if the accident is bad enough, you should get pictures of skid marks on the road or anything else that shows that the other driver was traveling at higher rate than they say.
We’re all human; we’re all curious. But if you’re rubbernecking at an accident on the highway, you could actually end up causing an accident yourself. Stay safe and don’t be a distracted driver.