sorry to jump on your thread mate
- but I have a rattle in my MKV it's coming from the rear passenger side corner of the boot... it sounds like it's the parcel shelf rattling... but I have tested this by removing the parcel shelf and I still get the rattle.. any ideas what can rattle at that end of the car?! 
I know this is a very old post, but I thought I would quote it anyway!!
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I had a similar rattle which was a complete mare to find. Having stuck my wife in the car behind the rear seats (
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) we found that the noise was coming from the very nearside of the tailgate. After much searching for something loose I took out the lens which is on the tailgate and discovered that the internal part of the lens was loose. It wasn't very easy to relocate it as it is a sealed unit, but I did manage and the rattle is now gone.
A rattle I had at the front turned out to be the plastic trim under the dash just above the pedals.Ireseated it correctly and now the car is all quiet again.
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TonyZ