Mirrors

The puddles in the street outside S'Artagnon's appartment caught my attention.

There was one scene in which someone galloped their horse madly up the street to get somewhere fast. In that scene, the hooves splashed water all around.

In one of the earlier scenes, there were no puddles, but instead it was supposed to be dry and the "puddles" were replaced by hollows in the dirt, as they should be.

But in another scene, in which Constance showed up in a carriage and got out ... The "puddles" were there, and the hooves and the wheels went through, but there was no splashes or wave action.

I think, at that point, the crew had inserted mirrors partially covered with dirt.

It makes sense. Water splashes would persist from one take to another, and water could show up on the wagon wheels and in the form of "tracks from previous takes". And to do a "dry dirt" take afterwards, they could just pull up the mirrors.