Is ONE PIECE episode 254 filler?
Canon No, episode 254 of ONE PIECE is canon.
#254
Nami's Soul Cries Out! Straw Hat Luffy Makes a Comeback!
ナミ魂の叫び！麦わらのルフィ復活！
Aired 22 Jan 2006
Mochibayo compiled this list from MyAnimeList's labels, because MyAnimeList's episode data is not reaching us at the moment.