Changing the interpolation of a rigid body doesn't update in the editor properly. Reopening a project with interpolation set, it then works. Sometimes changing from standalone to iOS will fix it, but reopening the project is the sure way to get it to work.

To reproduce:
A. Open the attached project, open Test Scene
B. Press play. You should see the cube move across the screen, but not smoothly. It should jerk. If you do not see it jerking, then try quitting Unity and relaunching. It should be jerky because it's a Rigidbody GO and we're moving it outside FixedUpdate so it should always jerk.
C. Click on the Cube GameObject in the scene and change the Rigibody component's Interpolate property from "None" to "Interpolate"
D. Press play. You should see no change. The cube still doesn't move smoothly, but it should because we now said it should be interpolated.
E. Save scene.
F. Choose File->Open Project… and reopen the project
G. Press play. You should see the Cube now moves smoothly.
So it looks like changing the interpolation property isn't correctly being updated in the player within the editor.