Hey, if there's a style that appeals to you and the design team approves then you put it in >> no question! But I'm always looking for that cultural thread for what makes the style and subject matter go so well together. Like the Lotr dwarf helmet was just begging to be used. And perhaps there's a bit of starship troopers in there as well, at least I'd assume so.
Honestly, I think the knit cap might not have any particular reference to it other than "knit caps are cool" :D