The first thing you hear from a goblin is a call to his friend "Rakanishlol".
Also, the bleak village in the middle of the swamps in Chapter 9 features what anyone familiar with the game will instantly recognize as the Tristram music from Diablo (even though it's actually not, obviously).
A wizard studying a dead moose in the first chapter mentions that "only goblin rangers are so precise".
You find two dead burned corpses in front of a burned farmhouse in the beginning of Attack of the Goblins who resemble Owen and Beru's corpses.
During the city assault portion in chapter 4, you and three NPCs will get surrounded by enemies in the town square. One of the NPCs, Admiral Agnar, shouts, "IT'S A TRAP!"
After the wizard holding the King hostage at the end of chapter 4 is defeated, he begins charging a massive lightning spell, only to have the king pick him up and throw him down a conveniently placed shaft as electricity arcs around him.
There is a lightsaber to be found next to a charred skeleton lying by a lava river...
The Yeti from SkiFree didn't forget you; it just patiently waited until you decided to play Magicka.
Fittingly, the first time you encounter a yeti (or "Snow Troll") is at the beginning of the snow chapter. You see a soldier skiing down a snowy mountain, jumping off a rainbow-colored ramp shortly before the yeti devours him. Also, while the other trolls are very slow and the Cave Troll's instant death attack takes a long time, the Snow Troll is really fast and it devours your wizard in less than a second.
Other robes include the "Reddit Robe", whose staff is topped with the Reddit mascot's antenna and wields and a "Votal Sword" (shaped like an Upvote arrow), the "Which Dr." robe, who wields a "Sonic Tuning Fork" and wears a fez, and the "Epic Sax Robe", presumably named after Epic Sax Guy.
There's a skeleton wearing brown shorts and a teal shirt lying on the floor of a tomb. Upon examining it, you're told that it "seems she was raiding this tomb".
The developer commentary / Let's Play elaborates that this reference was meant to go even further by having "milk jugs" on the floor as well.
James Bond gets an obvious reference in Chapter 4, both in dialog and in the way the boss decides to kill the king using a ridiculous contraption.
Chapter 3 gives us a twofer in the form of a stone circle with some druids and the corpse of a knight in blue. When engaged in combat, the druids shout "Shrubbery!" and "Ni!". The description for the knight says that he looks like he's had a really hard day. The sheer amount of blood and gore in the game is very much reminiscent of Moonstone as well.
The bosses of Chapter 8, the goblin ruling body, are referred to as The Aristocrats. The achievement for defeating them is called "More like The Aristocats".
One shout out doubles as a Stealth Pun - at one point you encounter a goblin archer wearing a green shirt and a hat straight out of the Errol Flynn film, making him of course Goblin Hood.
When the troll breaks through the encampment gate near the start and the captain yells "Vid Balder's Balle!" ("By the ball of Balder!" - and yes, it's the genital kind of ball), it's a shoutout to the Swedish viking sitcom Hem Till Midgård.
"The Stars are Left" has the Enderman from Minecraft, another Swedish game. And it's a much deadlier foe here, as it can teleport to you and pull a One-Hit Kill!
The Wurstmacher in Dungeons and Demons DLC is a pretty obvious one to the Butcher from the Diablo series.