World of Warcraft has always been notorious for having tons of video game and pop culture references and Mists of Pandaria tries really hard to set a new record. Here's what we dug up so far. Let us know in the comments if you've found others.
Mild spoilers below!
The quest mob Cracklefang in the Kun-Lai Summit zone is an obvious reference to the boss Sif from Dark Souls. He is much easier to defeat as you can see in Samdecahedron's video.
There's a quest called Bottletoads in the Valley of the Four Winds referring to—guess what—the NES classic Battletoads. The quest ends with the "Now when the kids ask "Do you have Bottletoads?" I can say YES" quotation. Some might remember why it's worth mentioning. Here's a video showing the whole quest.
During the escort of an NPC called Koro Mistwalker—as part of the quest Unsafe Passage in Krasarang Wilds—he takes an arrow in the knee. Here's the video of it from user Arthuras.
Seems like Peppy's annoying order from Star Fox got its own quest in Kun-Lai Summit. The quest seems to be fun though, as the video shows.
The whole "Tillers" faction in the Valley of the Four Winds is a shout-out to the Harvest Moon series (there's even a Blue Feather item). They're slightly different from the ordinary factions in WoW; you have to harvest crops and manage your farm in Halfhill in order to increase your reputation with them. Samdecahedron's video shows the intro quest line for the faction.
The quest I Have No Jade And I Must Scream in The Jade Forest is a reference to Harlan Ellison's horror/sci-fi short.
Using the quest item Nectarbreeze Cider on the Gormali Incinerators during the quest Spitfire in The Jade Forest will make them say "My eyes! The goggles do nothing!" which is from a memorable Simpsons episode.
There are already many Monty Python related stuff in WoW, but it seems Blizzard can't stop adding them. The Darkmoon Rabbit is the latest, referring to the Rabbit of Caerbannog from Monty Python's Holy Grail. It's a level 90 raid boss, so it's not an easy kill. You can watch an attempt in Kingxcommander's video.
There is an NPC called Grohl Grohl in Kun-Lai Summit who also appears to be a drummer, just like Dave Grohl. Youtube user Zadster shows where to find him.
The Singing Pools in the Pandaren starting zone is a sweet reference to the Cursed Pools Of Jusenkyo in the classic anime, Ranma 1/2. Lordthawkeye shows it in his video to the left.
Lon'li Guju might be the memento of the once world famous Pinta Island tortoise Lonesome George. He spawns in the northern part of Kun-Lai Summit. Youtube user Syiler gives you a hint where to find it.
Duke Nukem is also in the game under the alias Dook Ookem.
The Truffle Shuffle quest in the Valley of the Four Winds is a nice reference to poor Chunk's dance attempt in The Goonies. This daily quest can be obtained from Jian Ironpaw, shown on Wowhead's image to the left.
The NPC called Cornan The Barley Barbarian in the Valley of the Four Winds could be the gardener version of Conan. Image courtesy of Wowhead.
Kher Shan might be a reference to Shere Khan in Jungle Book. This creature spawns in The Jade Forest. Wowhead to be thanked yet again.
Red Blossom Leeks, You Make The Croc-In World Go Down, a quest in the Valley of the Four Winds rhymes with the lyrics of Queen's Fat Bottomed Girls. Wowpedia brings you the image.
Let us know if something is missing!