One thing I’ve noticed, is that while building long roads (usually those that are more than four or more blocks wide and 20+ long), it seems like some pieces of the ground will not be mined out before a block is placed down. This seems to be a result of the new building system where more than one block is placed at a time during construction, as if there is a piece of unmined ground next to a spot a Hearthling is going to build on; instead of being built around or skipped for the time being, the block is placed down in the already-existing ground piece.
Here is a screenshot of this such occurrence:
