"El Lazo" can mean "the loop", "the lasso" or "the noose" in Spanish.
Contrapasso is Italian for suffer the opposite. According to the Cambridge History of Italian Literature, it "functions not merely as a form of divine revenge, but rather as the fulfilment of a destiny freely chosen by each soul during his or her life."
This is the first episode that doesn't open with Dolores at the very first frame.
The melody heard in the background of the brothel scene, starting approx 37 mins into the episode, is "Something I Can Never Have (Still)" originally composed by Trent Reznor for Nine Inch Nails' 1989 debut album, Pretty Hate Machine. The version of "Something I Can Never Have (Still)" used in the episode is very close to the "deconstructed" version of the song was also included in Nine Inch Nails' live 2002 album "And All That Could Have Been". The original song deals with suicidal themes and was also used in the film Natural Born Killers.
The tune played by the pianola as Ford leaves the Man in Black in the saloon is a vastly sped up and highly corrupted version of Scott Joplin's Pine Apple Rag.