is attack on titan (shingeki no kyojin) episode 37 filler?

Memories of his mother's life and death flash through Eren's mind then the smiling Titan that killed her five years ago appears on the battlefield. Elsewhere, Reiner continues to throw Titans at the retreating Scouts.

Ymir brawls with the Titans, outraged at Commander Erwin's hand in her plan's failure, and the commander is dismounted when she attacks a Titan pursuing him. Erwin's Scouts attempt to defend him, though Erwin places Eren's life above his own for the sake of the mission.