When planting seeds, ( I have only noticed this in carrots and wheat)  it will occasionally spawn a fully mature plant. 

When farming a 3 block tall sugarcane, the top most block will remain floating after broken.

Certain redstone functions do not work when transferring power from block to block. (unsure if this was intentional, see attached image) In this image the power from the redstone torch should have passed through the block on the piston but did not. Also on occasion, sticky pistons will not grab other pistons or sticky pistons.