is attack on titan (shingeki no kyojin) episode 19 filler?

Still being chased by the Female Titan, the squad begs Levi for orders, proposing to engage in a fight with the Titan. However, Levi tells them to cover their ears and, much to their surprise fires an acoustic signal in order to remind them of their job, which is making sure that Eren is not injured even if it costs their lives.

This leaves Eren surprised as he was under the impression that they were just keeping watch on him. Levi then orders them to keep going on horses.