ムダ足だった == useless leg? When I look up the phrase , I see it translated as "It was a Wild goose chase." I found this bizarre, since it seems like it would mean "It was a useless foot/leg." is this some sort of figure of speech that means the same or something similar to "wild goose chase" or am I missing something? Thanks for any help.

I believe []{} is derived from []{}[]{} ("move one's feet in vain"), which is one of a series of counterintuitive idioms Japanese vocabulary has.

* **[]{}[]{}** "little stomach get empty"
actually describing "be a little hungry" (cf. []{}[]{} "be hungry")
* **[]{}[]{}** "blow on a big conch"
actually, "blow on a conch loudly" or "tell a tall story" (cf. []{} "talk big")
eventually []{} itself stands for "tall story".
* **[]{}[]{}** "push a side cart"
actually, "push cart from the side" or "ram through"
eventually []{}, "unreasonable demand".
* **[]{}[]{}[]{}** "be pulled by the rear hair"
actually, "be pulled by the hair from behind" or "too sorry to leave"
* **[]{}[]{}** "break a useless bone"
actually, "break a bone in vain" or "make vain efforts" (cf. []{}[]{} "make efforts")
eventually []{}, "vain efforts".