JBif both of you had your cam chain slip off and you didn't suffer catastrophic damage, you are extremely lucky! The cam chain tensioners on certain bikes 12'-14' are under recall and may be replaced at BMW's expense. I just had to have my 14' (not under the recall) cam tensioner replaced to the newer Hydraulic model because my tensioner was starting to fail. If your chain slips and throughs the timing off, the valves and pistons collide and ruin the engine completely unfixable outside of engine replacement. I strongly suggest you look into getting it fixed, my was a $1000 but better than the $7000 engine replacement on a bike worth $4500.
If you are hearing a "rattling" noise from the engine, do not ride it. Unfortunately, it will be become a very expensive paperweight if you continue to do so.