Why is Franky's Strong Right a rollercoaster car? When watching episode 583, I noticed that Franky's Strong Right attack looked like a roller coaster car. Is this just a design choice or some hidden pun?
According to Frankie article on One Piece Wiki that is actually meant to be a flame-shaped plate.


  Strong Right (ストロング右（ライト） Sutorongu Raito?): A new version of the original Strong Right, Franky launches his much bigger right fist at his opponent akin to a rocket, with a chain to retract it. The fist also has flame-shaped plates on the sides with "STRONG" written on them that seem to be purely for aesthetic design. His fist also seems to have an electrical charge. This was first seen used against the attackers on Punk Hazard.


This indeed make much more sense than a rollercoaster car and is more fitting with Franky robot style.