What I expected to happen was...:
Left click to exit stationary mine cart OR hit mine cart to exit and make it a resource.
What actually happened was...:
Nothing on left click and right click attempted to destroy the block under the mine cart.
I was not able to exit the mine cart at all until I restarted the game in the previous version op my system (1.5.2)
Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
3. ...
I think they changed it so you have to hit LShift rather than right-clicking it.