Goombas have arms and hands. They are folded neatly behind their backs. pic.twitter.com/nRXVi6u92f— Joe Piconi (@joepiconi) April 19, 2019
Goombas do not have arms. They just waddle around on their legs and that's that. At least, that's what we thought. The figurine above, which does appear to be a legit Nintendo release, shows that somewhere along the line, Nintendo was considering a set of arms for the little guys.
Obviously, it appears this idea has long since been dropped. Goombas have appeared in countless games over the years, and not once have we seen them with a pair of arms. While it might be a little freaky seeing Goombas with arms nowadays, I think an arm reveal would make for a pretty funny one-off gag in a Mario RPG!