General Maintenance & Repairs - rattle in reverse

well... my car is completely stock right now and the exhaust seems to be

rattling like hell...especially in reverse even when im not moving....i have a

random misfire in my engine right now (getting fixed) could this be the

reason for the rattle....

Could be engine/trans mounts are getting loose and are letting your pipes smack the floorboard. what is with the missfire? plugs wires? coil?