For the most part I didn't see any garbage mattes. It looks really good overall.

The ones I did notice:

-In the middle of the fleet jumping into hyperspace shot.

-A little barely visible here and there during the speeder bike chase.

-Around the edge of the Death Star, especially noticeable around 1.25.42

-Around the Death Star when the fleet comes out of hyperspace.

-In the tail end of the shot where Lando first approaches the Star Destroyers.

-In the TIEs through the Falcon cockpit shot

-On the Falcon at 1.36

-TIEs inside the Death Star at 1.52.50ish

-Executor plunging into the Death Star.

-Luke flying the shuttle out of the DS.

They really will be more noticeable during bright frames or flashes (laser blasts, hyperspace, explosions) and movement.