Did any of the films include pop culture references? I don't remember any.
There are scenes with robots from Silent Running.
There's a scene where you see a giant snake skeleton on Tatooine that's supposed to be a nod to Dune.
More "inspired by" than references...
Obi-Wan is a Gandalf clone. His character arc in 4 is identical to Gandalf's in Fellowship.
Dune is heavily borrowed from.