Using the strong attack (hold X) with the large kitchen knife you can find in the diner will make Chuck grab a zombie around the waist and stab it in the chest repeatedly while the PsychoScare Chord plays.
There are cardboard standees of Proto Man in the town movie theater.
There is a Blue Badger graffiti on the wall in the town.
One of the masks is a "goblin mask" that is clearly Blanka from Street Fighter. Furthering the homage is a combo weapon - take the mask, add some batteries, and you have an electricity-spewing Blanka head!
One boss fight with Sullivan should possibly remind of another hand-to-hand boss fight from the first one. Especially because you can get disarmed from any weapon unless you fight with your fists.
The host and announcers - and the show in general - of Terror Is Reality is one big Shout Out to a similar pay-per-view event, up to and including the host serving as the final boss of the game, taunting you all the while.
Yet another and possible subtle one, The Running Man complete with a jumpsuit that matches Arnold's one in the film, and the fact TK is much like Killian (the Big Bad, an egotistical Jerkass, and someone who uses a loved one for entertainment value).
Brandon has a button on his shirt that resembles the Umbrella logo.
Many of the Psychopaths in the sequel bear strong similarities to ones from the first game. A few examples:
Chuck's rival Motocross racer/Terror is Reality contestant Leon Bell (Kent). Also, y'know...
Seymour Redding, a power-tripping security guard who's big on public executions (Jo, Sean to a lesser extent).
Cannibal chef Antoine Thomas (Larry)
Brent Ernst, a socially inept pyromaniac teenager in a mascot costume (Paul, also Adam).
Bibi Love, a crazed pop singer with a literally captive audience who eventually comes to her senses and can be rescued (Adam, Sean, Paul).
Some of them die similarly to the psychopaths in the first game, like Randy dies due to a victim he just recently killed, ala Cletus.
"Look, Dad, I just got a new power in Mega Man!" There's also a store called "Wily Travels" whose description on the map is a hurricane of Mega Man references, and they even have Proto Man as a mascot!
Next to it is a store called Albert's Apparel.
The Laser Sword is made by combining the flashlight with gems, meaning it's effectively a low-budget Lightsaber.
The battle with the twins appears to be a shout out to Streets of Rage. Fighting sexy evil twin ninjas in an ocean-themed nightclub with electronic dance music blaring seems to be more than a coincidence.
Katey has a Slime keychain on her backpack, and the text "Puff Puff" on it is a reference to a vaguely sexual Running Gag in the series.
Combine yellow suit with knife gloves for low rent Wolverine cosplay.
For whatever reason, the survivor you rescue from Seymour, Ray Teller, looks exactly like Kevin Bacon.
The quest "WWJWD" is short for "What Would John Wayne Do?". He probably wouldn't start hanging innocent people for shits and giggles...
The Magician Psychopath Reed resembles Will Ferrell, although he and his partner dress like Siegfriend and Roy and use a feline in their act like they do, while Roger's apparent muteness and the fact that he's noticeably shorter than Reed is similar to Penn & Teller.
There's a group of four nerdy guys who show up in South Plaza on Day One, although a lot of players will miss them due to how the game handles spawn timers. The group consists of Steve Urkel, Dr. Horrible, a fat guy in a fuku, and their comparatively normal friend. They're playing a very familiar roleplaying game.
The female poker player in the secret group of survivors in the Atlantica casino appears to be an expy of Jennifer Tilly, who is known for her poker "strategy" of letting her boobs spill out all over the table. One of the other poker players that make up the secret group, Nevada Slim, looks like real-life professional poker player Greg Raymer.
Also, the Paddlesaw is pretty much a homebrew edition of Skorge's dual chainsaw staff.
The rock band Angel Lust appears to be a joint project between Marilyn Manson, Tommy Lee, and Amy Lee, although they hired a really terrible songwriter.
In a reference to two other famous British bands, one of the band members is named FloydStone.
One outfit is a fruity biker getup complete with assless chaps. It is named the "Blue Oyster" after the Gay Bar in Police Academy.
You can find Borat's banana hammock. When you put it on, Chuck dances around and says "I'm a big boy now!" and AVERT YOUR EYES.
An achievement/trophy is called "He Hasn't Covered Wars..."
You're able to get knight armor that makes you look like Arthur from Ghosts 'n Goblins, and when it shatters you're left in nothing but your underwear.
Lenny, an autistic man you can find in the back room of the Yucatan, talks about his affection for numbers and his rich brother Charlie while you're rescuing him. Upon returning to the safe room, he even claims to be an excellent driver.
The image painted on the doors of Leon Bell's bike trailer looks like a callback to the tattoo that Steve-o from "Jackass" has on his back.
Sgt. Boykin spouts Hudson's lines from Aliens in a cutscene. And when he dies, he suicides himself with a grenade like Vasquez.
After the S Ending, a zombie pops up like in the infamous K-Fee energy drink adverts.
Three sexy girls who are associated with "Guardian Angels" protective services. Charlie's Angels, anyone?
You can find a comedian named Walter Morris who's dressed a lot like El Chavo. And a possible shout out to Fargo, his notebook description reads "Kinda funny looking".
When Chuck is idle with a sword, he slices the air and examines the sword. Sound like another green hero?
Down in the maintenance tunnel that connects the holding pens to the harvesting room, you can find a message scrawled on the wall in blood that reads "DONT STARTLE THE WITCH!" accompanied by female sobs echoing up from a nearby ventilation grate.
When shooting security cameras, Chuck will sometimes say "Good night, Big Brother!".