is attack on titan (shingeki no kyojin) episode 20 filler?

Following the capture of the Female Titan, Eren questions its identity, wondering if it is an abnormal or something like the Colossal Titan. Oruo and Petra interrupt his thinking and tell him to focus on getting farther in and standing by.

Meanwhile, Levi readies himself to strike the Female Titan, however, Erwin is not satisfied with just trapping the Female Titan and orders the soldiers to fire the rest of the wires. At the outskirts of the forest, the soldiers continue making sure that no Titans get inside.