is attack on titan (shingeki no kyojin) episode 15 filler?

With Eren now being an official member of the Scout Regiment, he is escorted to their former HQ. Riding horses to get there, Oruo Bozad explains to Eren that it is in fact an old castle they remodeled.

In the end, it ended up being useless for the Scout Regiment, but it will now serve as a hideout for Eren. Afterward, Oruo attempts to intimidate Eren, but thanks to his horse stepping on a rock, he bites his own tongue, much to Eren's startle.