I'm sure every Goonies fan out there is familiar with the bowling ball trap that One Eyed Willie had set.

Well the key that is removed from Mr Copperpots dead body that Mikey obtains is used right before the bowling ball scene. It's when he fits it in the circular wooden device and spins it counter clockwise. His hand is clearly stuck and he cannot remove it even with Mouth and Data pulling him he wont budge, then the ground gives way and Data falls to another room with spikes. As soon as the camera pans up and shows the rest of the crew looking down to see if he is okay Mikey is free.