handbrake cable come off right side rare

im in a parking lot getting ready to leave started the car put gear in reverse pulled the handbrake down it seemed ok as i could feel the tension on it.so im headed home pulled into my driveway which has a slight dip then flat surface.i put the foot brake on then gear into park pulled the handbrake up and thats when i felt it had no tension so i took my foot of the brake the car then moved forward abit.i checked underneath and noticed the right rare cable had disconnected from the clip and the holepin which also had come off.i guess my question is what could have caused this to happen?im hoping its just reattach the cable to the clip an holepin an reconnect it if its not seized.i dont know much about cars but the problems i come across with mine I'll ask questions,learn and solve em myself if its not a major lol an thanks in advance.