The Lifted Riffs is a knock-off of Led Zeppelin.
The scene where the guitar player is using the violin bow is a tribute to Jimmy Page. He used a violin bow during his guitar solos in live shows.
During the showing of Colt Luger Bill is watching, there is a reference to the painting Ecce Homo by Elías García Martínez in which Cecilia Giménez attempted to restore but failed in the process.