Nice episode, although it is still filler, I quitely enjoyed it especially because nothing was contradicted, although they didn't get Hagoromo right. I mean Hagoromo would never said that he couldn't do something like his son as he was vastly supperior to him, period.
With Rinnegan he can learn anything at whim, so no period failed to portray Hagoromo well as father. Same with Hagoromo not confronting Indra after he becase to behave suspicious, it just doesn't make sese to let your kid go wild and do not confront him about wrong stuff.
And lastly black zetsu indeed idiot to tell Indra that he will even rival Hagoromo(unless he mean very old Hagoromo as before dying). End of my rants