is attack on titan (shingeki no kyojin) episode 32 filler?

Three years ago, Reiner and Bertholdt wander through the forest outside the 104th Cadet Corps training grounds, discussing their reasons for joining the military with Eren and Armin. Reiner states his need to return to his hometown, and Bertholdt wants to join the Military Police to live safe in the interior.

Eren says that he wishes to slaughter all the Titans beyond the Walls. Coming to a cliffside, the moonlight shines through the clouds, illuminating a large lake in the valley below.

Reiner is surprised that Eren's will was not broken by the attack of the Titans.