Is ONE PIECE episode 505 filler?
Canon No, episode 505 of ONE PIECE is canon.
#505
I Want to See Them! Luffy's Mournful Cry!
あいつらに会いてェ！ルフィ涙の叫び
Aired 3 Jul 2011
Mochibayo compiled this list from MyAnimeList's labels, because MyAnimeList's episode data is not reaching us at the moment.