Is ONE PIECE episode 494 filler?
Canon No, episode 494 of ONE PIECE is canon.
#494
Here Comes Sabo! The Boy at the Gray Terminal!
サボ登場！不確かな物の終着駅の少年
Aired 17 Apr 2011
Mochibayo compiled this list from MyAnimeList's labels, because MyAnimeList's episode data is not reaching us at the moment.