When Galaxy Note 5 was introduced, it had one serious problem with its S Pen. If it is placed upside down, it gets stuck and can only be retrieved with a lot of damage. The sensor gets damaged and screen cracks. Previously many people tried to find solution to this problem but were unsuccessful.
However, Sammy has taken care of this problem in next devices.
Learning this from Note 5 experience, the company has made Note 7 free of this error. So you may not get stuck one you place the Pen Upside down. The company has made it impossible to place the pen wrong way, due to which, it may not lead to any problem at all.