Orange-Nassau brought the golden Lion and the golden rectangles (Billets) on a blue Field. The Dutch Republic brought the Arrows and Sword to put in the Lion's hands, the Coronet (which became a Crown and was later reverted to a Coronet by Queen Wilhelmina) to put on the Lion's head and the two Lion Supporters.
These Supporters started out as guardant, in other words facing out towards the viewer, and were crowned like the main Lion. In 1907, Queen Wilhelmina not only changed the Crown on the main Lion in the Shield back to a Coronet, she also removed the Crowns form the supporting Lions completely but also made them face in to the Shield. (They had briefly faced into the Shield under William VI until 1815.)
One other thing changed. The two Lion Supporters had been gold in the Dutch Republic and that's what they are again today (or, as of 1907). In between 1815 and 1907, however, they were the natural colour of brown. (This style of showing the natural colour of anything in Heraldry is called proper.) The Belgian Supporters are still shown as proper mainly because the Belgian Coat of Arms was agreed on in 1830 and matched its neighbour being derived from the Dutch Republic as well.
In around 1665 or 1668, the colours of the Coat of Arms were reversed to better represent all the Provinces of the Republic, not just Holland and here, I believe is where some confusion may have arisen. You would imagine that the Supporters would have likewise changed from red to gold. If you look at the middle picture above of the stone carving of the post 1665/8 Arms on the fireplace in Delft, are the Lion Supporters really left natural stone...?