Rear hatchback door rattle/sound-subwoofer

[Pinchlite]

Figured this would be best place to post.I have ported 10''sub facing towards back inside of hatch door.Clearance is about 3 inches.

There is something insanely vibrating from the rear door.It is not the licence plate as this seems the first thing people seem to assume.

Perhaps other hatchback owners can give me an idea where to look.Personally I think it is inside the door itself?

Facing the sub upwards does not eliminate rattle.

P.S

There is plenty of other rattles aswell.One that is most annoying is the rearview mirror.It is not the mounting but the actual casing of the mirror inside the enclosure.I may just replace mirror to fix this.