History ShoutOut / Portal

** Or not.

* The Bots trailer features ATLAS [[https://www.youtube.com/watch?v=W_gxLKSsSIE holding a frying pan with a pancake]]. A bit of a TakeThat with ATLAS[[https://www.youtube.com/watch?v=AZMSAzZ76EU just not doing it right]].

* A DummiedOut line from co-op mode's original plot involving [=GLaDOS=] trying to get Atlas and P-body to behave more like humans involved them bringing back a comic strip about [[ComicStrip/{{Garfield}} a cat who freeloads in a man's house and eats all his lasagna]]. [[SeinfeldIsUnfunny She's not very impressed]], and [[Webcomic/GarfieldMinusGarfield decides to rework it]].

* There's a science experiment that resembles a [[Film/BackToTheFuture Flux Capacitor]].

* One of the universes has Cave running testing on a satellite orbiting and trying to discourage test subjects from trying to discover the "big conspiracy" (which is that they are in space) because they keep breaking through the walls, probably a parody of ''Film/DarkCity''.

* One of the universes has Cave running testing on a satellite orbiting and trying to discourage test subjects from trying to discover the "big conspiracy" (which is that they are in space) because they keep breaking through the walls. This might be a reference to ''Film/DarkCity''.

* One of the Achievements is called "VideoGame/NarbacularDrop", a shout out to the student project that eventually became ''Portal''.
* The Bots trailer features Atlas [[https://www.youtube.com/watch?v=W_gxLKSsSIE holding a frying pan with a pancake]]. A bit of a TakeThat with Atlas [[https://www.youtube.com/watch?v=AZMSAzZ76EU just not doing it right]].

* Rick, the Adventure sphere says that he's got a belt in just about everything, from Karate to [[http://www.teamfortress.com/war/saxtonhale/poopyjoe.htm Larate]].

* One of the Achievements is called "Narbacular Drop", a shout out to the student project that eventually became ''Portal''.

* Caroline's line "Goodbye, Caroline!", to ''Series/LaughIn'', which always ended with "Say good night, Dick!" "Good night, Dick!". Ironically, it was likely intended as a ShoutOut to the BurnsAndAllen Show instead, since legend has them ending the show with "Say good night, Gracie!" "Good night, Gracie!". However, Burns and Allen [[BeamMeUpScotty never actually used that line]]. Burns and Allen would have been on the air when Cave and Caroline made their recording, and ''Series/LaughIn'' did not start until 1968, so it's more probable that the writers meant it to be a BurnsAndAllen reference.

* One of P-body's dances makes her do a spinning dance, before stopping and shooting a Portal straight forwards. This may be a reference to the dance the Wizzrobe from ''VideoGame/TheLegendOfZeldaMajorasMask'' preforms before attacking Link.

* In the ending, something flat (the monitor screen) flies by and Wheatley drifts forward, much like ''Series/TheTwilightZone'' opening credits.

* Doug Rattmann's den in the Companion Cube level also contains a rather well-hidden shout out to Creator/IsaacAsimov's short story "Escape". His dens all have some poems altered to include cubes and the like. [[http://half-life.wikia.com/wiki/Doug_Rattmann#Graffiti_list Here]] is a full list of the graffiti drawings.
* "Delicious and moist" cake was originally a joke in ''VideoGame/{{Psychonauts}}''.

* In the testing room for military androids, [=GLaDOS=]'s dialogue implies that robots and androids are programmed with a belief in "Android Hell" in order to ensure their compliance. This shouts out to ''Series/RedDwarf'', wherein robots and androids are programmed with a similar belief in "Android Heaven" for a similar purpose.