Is ONE PIECE episode 670 filler?
Canon No, episode 670 of ONE PIECE is canon.
#670
Dragon Claw Strikes! Lucy's Intimidating Attack!
竜の爪炸裂！ルーシー脅威の一撃！
Aired 16 Nov 2014
Mochibayo compiled this list from MyAnimeList's labels, because MyAnimeList's episode data is not reaching us at the moment.