Its also the only national anthem to mention Sweden by name! [1]

[1] Sort of. The thing is that Sweden does not have a national anthem as such: it has a popular song about that nation that functions as the national anthem. But it does not have an official one. These first two verses are the original ones, written in the early 1800's, and gained its status as de facto anthem by way of popularity: the reason we haven't officially named it the national anthem is due to a feeling that it is unnecessary: it has been elected by informal popular demand.

This song, "Du Gamla, Du Fria" (Written by Richard Dybeck) is more of a pan-Scandinavian paean (Since we were in union with Norway at the time) to the nations lovely landscapes of our land. See: Thou ancient, thou free, thou mountainous north Thou quiet, thou joyful [and] fair! I greet thee, most beautiful land upon earth, /:Thy sun, Thy sky, Thy meadows green.:/ Thou art enthroned upon memories of great olden days, When honoured thy name flew across the earth, I know that thou art and wilt remain what thou wast, /:Yes, I want to live, I want to die in the North.:/

Due to its informal status, anyone could add to it and claim it to be part of the national anthem. Thus, in the late 1910, when nationalism was running high, at least one person (Louise Ahlén) added verses which glorify Sweden's more militaristic accomplishments, and a general, specific nationalism. See:

I forever want to serve thee, my beloved country, Loyalty until death I want to swear thee, Thy right I will protect with mind and with hand, /: thy banner, the heroes carry high.:/ With God I shall fight for home and for hearth, for Sweden, the beloved native soil. I trade thee not, for anything in a world /: No, I want to live, I want to die in the North!:/

These verses are not sung often (I've read that they are sung in nationalist and neo-nazi circles, but I'm unsure about the veracity of that claim), and are not included on the royal court's recommendation, and most Swedes (I'd hazard to guess) are utterly unfamiliar with them.

So, it's basically true that the Polish national anthem is the only one to mention Sweden.