Rigid bodies not colliding when going fast I have a scene with (what will be) a treasure map and am trying to animate some coins falling onto it. I started based on this tutorial https://www.youtube.com/watch?v=iYL9w6xsZ6g made a coin, animated its rotation for the first frame and then animated turning off animation. Everything works perfectly if the coin drops from 2 blender units or less, but if I move the start position higher then the coin passes straight through the map mesh.

On the map mesh I have rigid body passive, shape: Mesh, Source: final
On the coin mesh I have rigid body active, shape: convex hull, source: deform

I also encounter the problem if I start duplicating the coins at around 2 Blender units high, some will pass through and others will collide.

My coin is 0.237x0.237x0.047 and my map mesh is 0.02 units thick (though I've tried making it thicker and it didn't seem to help much) I'm using the Blender 2.78 release candidate
Try scaling up your entire simulation. 

You could also try changing the hitbox type of your coins from mesh to cylinder or cube.

The manual page about soft body collisions may help you.

It explains how the collision system works, and why your objects do not collide with the ground material.