STOP
my friend had some one do that to him and didn't know until to late had to replace oil pumps both and lots of other internal damage.
you need to get it out ASAP you could take off the top cover to give you a little more view and access maybe a magnet and string or stick.
At worst you will need to either pull the motor or pump to give access to the pto housing you will have to split to get it out
PS WHAT A **** DESIGN BRP who thought of that design must have been pissed WTF