So this was my thought process during this episode:

A gold gun? I mean, I get a cold gun, sure. And a heat gun, fine, that's basically a flamethrower. But a gold gun? Does it create liquid gold? Turn things INTO gold? I mean, if it did, why would they need to rob anything at all? WHY NOT TURN THINGS INTO GOLD THEN?

I mean, this isn't even from the comics. In the comics, Lisa Snart was called the Golden Glider because she had, like, ice skates that allow her to skate anywhere, even in mid-air (also, she wore gold? I think?). And in the New 52, she had some sort of astral powers. There is nowhere in the comics where she has a gold gun.