In The Barrens, there is a tombstone complete with a Spirit Healer, known as The Shrine of the Fallen Warrior. This is a shrine dedicated to Michael Koiter, a designer of World of Warcraft who died during development due to heart failure.
While fighting your way through the Deadmines to get VanCleef's head you'll encounter a Goblin Shredder. Take it down and look at the dashboard and you'll see a familiar face: Kerrigan, The Zerg Queen from Starcraft: Brood War. She appears to be the ruler of the goblins as well. Other goblin shredders can be found in Stranglethorn Vale and Gadgetzan.
The item "Six Demon Bag" is a nod to John Carpenter's Big Trouble in Little China: sorcerer Egg Shen's (Victor Wong) Six-Demon Bag has the power to blast enemies with "wind, fire, all that kind of thing!"
In the Lower City there are characters named Adam Eternium and Oric Coe. This is a reference to He-Man of course Prince Adam of Eternia and his sidekick Orko. This character also has his "Battle Tiger' instead of Battle Cat.
Similarly to the Alliance battlemasters in the Lower City of Shattrath, amongst the Horde battlemasters is Keldor the Lost, a clear allusion to Skeletor, He-Man's arch-foe, who's original 'human' name was Keldor. He even comes complete with the purple tinged skin and goat skull staff.
In the Badlands around the middle of the map is a semi-hidden crypt. Enter the crypt and you'll see a decomposed guy sitting on a throne with a sword to his side. A clear allusion from the first Conan film.
In Sporaggar, Zangarmarsh, the Sporelings give a quest called "We Want a Shrubery!!". This is an obvious reference to the film Monty Python and the Holy Grail (1975) in which the Knights Who Say Ni demand a shrubbery from King Arthur.
In Stormwind, the cooking trainer is named Stephen Ryback and the cooking supplier is named Erika Tate. This is a direct reference to the movie "Under Siege" starring Steven Segal who played Casey Ryback and Erika Eleniak who played Jordan Tate.
A further movie allusion comes from Star Wars. In the Shimmering Flats, peek around a bit and you'll find a goblin race team with a very familiar looking vehicle - Blizzard's version of Sebulba's podracer from Episode I. Do a little more exploring and you'll also find a wrecked podracer which smacked into a canyon walls.
Outside of Auberdine in Darkshore, a dwarf could be found named Glubber Bump. This is a reference to Forrest Gump (1994), when the shrimp company Forrest founds is called Bubba Gump. A quest given by Glubber is called "Fruit of the Sea" and Glubber details all the way you can cook crab. This is also from Forrest Gump when Bubba details all the way you can cook shrimp.
In Un'Goro Crater there is a questgiver named Ringo who gives out a quest called "With a Little Help From My Friends". "With A Little Help From My Friends is a song by The Beatles and Ringo Starr is a member of the Beatles
The NPC in the Lower City that gives the daily cooking quest is named Rokk - a reference to WWE Professional wrestler Dwayne "The Rock" Johnson who's tag line was "Can you smell what the Rock is cooking?"
In the Alliance city of Theramore in Duskwallow Marsh, there is a fishmonger who works on the dock named "Dirty" Michael Crowe, a reference to the host of the Discovery Channel's show Dirty Jobs (2005), Mike Rowe.