donpb

Yeah I've successfully fished items out with a mag extension and its not fun at times. I have the kind that has the grabbers and the mag. Often times, the grabbers are more helpful than the magnet.

I've since learned to jam a shop towel into any openings. I've dropped tools as well and the fix to that was to tie a long wire to one end.

dingolfing

Oh man, that sucks.

I heard that to remove the upper oil pan, you gotta drop the entire front subframe.

If you are sure the nut is inside the oil pan, why not use the magnet on the bottom side of the aluminum pan and see if you can "pull" it toward the oil drain plug. If the nut is small enough, you may be able to drain it along with the oil thru the oil drain opening.

Byootox

I Done this job on mine about 3 months ago, it was a bit of a mission to do it.
No4 and No8 inlets are a real stinker(back two cyls)
The intermediate shaft levers jumped out of place as well.
I eventually got pissed of with the things and just took out both cams and done it that way.
Only thing is you need to remove both front top timing covers to gain access to cam pulley bolts.
Timing tool for the cams is actually very cheap to buy.
I've done another much quicker since on a 7 series, much more room to mess about in these than the 5 series.
I've been on the tools for over 30 years but not much on Bimmers, my opinion... not a job to take on unless you've got a bit of previous experience or plenty time on your hands.
Once you strip the intermediate shaft assemblies it starts to all make sense how it works on the inlets.