Take pictures of your rental car
When you are renting a car, you usually get a record of all the dents and damages. But the staff can miss some minor dents and scratches (sometimes deliberately). Check the car yourself and do it carefully.
Take photos of the car, especially any anomalies you see. Try to make them as detailed as possible. That way, you can protect yourself in case they file any false claims. They can’t blame you for the damage that was already there.