Jens Stoltenberg, the prime minister of Norway, is playing himself.
Hans uses first one, then up to three sheep to lure out the troll under the bridge. This is a clever hint from probably the best known story in Norwegian - "De tre bukkene Bruse" - where three sheep are crossing a bridge to go to the other side to eat, but the troll under the bridge is trying the eat them. The smallest one tells the troll that the one coming after is bigger and better to eat, so the troll lets him go. The next one says the same, and the last sheep kills the troll when it attacks.
In one of the scenes Thomas ask the troll hunter jokedly what to do if a troll challange them to an eating competition. The reason he asks this is because in one of the best known Norwegian fairytale "Askeladden som kappåt med trollet" (which loosely translates to "When Askeladden (Ash Lad) and the troll had an eating competition") the main protagonist Askeladden defeats a troll by challenging it to an eating competition.
In the movie it's said several times that the trolls can smell the blood of Christians. This is a reference to the old Norwegian fairytale where the trolls often would say "I smell Christian man's blood!" when they encountered humans. This is the only "magical" ability the trolls have that made it from the fairytale in to the movie.
Hans Morten Hansen, the actor that plays Finn from Viltnemda holds the Guinness World Record for longest stand-up act. Took the record summer of 2010 with a show that lasted for about 38 hours.
Hans, the troll hunter, comments on the electric pylons stating he "thinks they look nice". In Norway there was a ongoing discussion on building more of them from Geiranger to Bergen (over the Geirangerfjord) in what is considered to be one of the prettiest and most known parts of Norway. As of October 2010 the discussion is still going, and one of the most known comments is that those pylons are ugly and would ruin the nature.