Mark, silent King, the moral of this sport,How soon my sorrow hath destroyed my face. (4.1.11)
Finding that his face doesn't "reflect" his new degraded state, Richard smashes the mirror and tells King Henry to look at how sorrow has "ruined" his face (actually the mirror). It's a smart switch: even more important than a "real" face, Richard seems to be saying, is the face's reflection. Smash the reflection and you also smash the thing it reflects. In other words, life is an illusion.
Twice for one step I'll groan, the way being short... (5.1.7)
In kind of a sweet moment, Richard promises the queen that, since she has a longer way to go, he'll groan twice as much so that they end up suffering the same amount. Notice that Richard has started using his expressions of grief to measure distance and, elsewhere, time.
His face still combating with tears and smiles, The badges of his grief and patience... (5.2.3)
York's description of Richard's humiliating walk is really moving and totally consistent with Richard's passivity. Even now, the only kind of "combat" he seems to be capable of is the combat of "tears and smiles."