Shout Out / Killing Floor
- Lots of them to Harry Enfield's Loadsamoney sketch character.
Money, money, money
- Taken Up to Eleven with the DLC character "Harold Lott", who is that character.
- "Who do you think you are, bleedin' Action Man?"
- "I know, you're only supposed to blow the bloody doors off!"
- The KF_Aperture map is an outright Crossover with Portal.
- The trailer for the Summer Sideshow event has a clot saying "Knife goes in, guts come out."
- There's also references to IT. The Circus Husk also has some very GLaDOS-esque lines.
- Some of the Christmas Zed quote I Just Want My Hula Hoop and Grandma Got Run Over By A Reindeer.
- The Gingerfast likes to quote the fairy tale of the Gingerbread Man, and the Snow Husk quotes Frosty the Snowman and The Christmas Song.
- The achievement for killing the Vampriarch in the 2010 Halloween Sideshow event is "Sparkling in the Twilight".
- The .44 Magnum is the same model as Dirty Harry's Weapon of Choice. Killing six specimens with one shot each without reloading unlocks the achievement "Feeling Lucky?"
- Equipping the knife makes you run faster.
- The achievement for killing one Clot for every bullet in a full Mark 23 magazine is named "Spec Ops".
- The Patriarch references Magical Trevor:
I'm back, and I've got some new tricks!