List of references

Within Portal 2, both in-game and in the trailers, are multiple references. There are a variety of references, mostly including games or parts of games.

Left 4 Dead series

 * During one of the pre-release trailers, Atlas can be seen wielding the frying pan, a weapon used by the survivors in L4D2.

Smash TV

 * One of the achievements labeled Smash TV is a reference to an early 90's arcade game called Smash TV, where two contestants are pitted in a brutal game show in which they're forced to fight for their lives for cash prizes.