Lying to the police and making a false report is a crime. Making a mistake by telling the police one thing, then remembering it’s another thing, is different and not a crime.
For example, describing the getaway car as red when you definitely know it was white is lying and thus committing a crime. But if you think the car was blue, but later remember that it was in fact green, is an honest mistake that you would correct yourself with the police when you recall that detail.
If the police approach and question you regarding anything you may have heard or witnessed, don’t panic and just blurt out anything. Think about what had happened. If you don’t remember something, be honest. That’s way better than lying, and then later finding yourself in trouble.