is one piece episode 664 filler?

With the Army moving out, the Thunder Soldier, Robin, Usopp and Franky move out. While Leo shows them a secret passage to the underground, Usopp notes its very narrow and Franky is too large to go through as he and Robin alone are barely able to fit.

Leo apologizes mentioning large humans weren't meant for the passage. Franky asks how he can find another way in and the soldier reveals he can go through the Toy House above ground, but is against that idea.