In Iberia in the era of this film it was common to display your wealth by having at least one prominent gold tooth - this is still usual in the African continent - and is for show, having nothing to do with a dental repair. Lupe Sino is depicted as enjoying the company of men, is frequently called a "whore" by Manolete's entourage (who disapprove of the relationship because they fear for their own status), and has a basket-crown on her upper left incisor - this is not the habit of a "respectable" woman in 1940s Spain. When she has it removed she shows Manolete by tapping her front tooth and saying "Look, respectable" and there is a huge close-up of her front teeth. Also, during the course of the film her wardrobe and hair-style become gradually less gaudy - her way of showing Manolete that she is willing to settle down and become a "respectable" woman he can marry.
About 7 minutes into the movie, a piece of source music is played. The scene has Manolete, holding a gun, looking for Lupe, after she presumably fled their bed. The song is played in a diegetic way, letting the viewer assume that it's coming from inside the movie universe and that the characters themselves are hearing the soundscape. The song is "Las Campanas de Linares" by Rafael Farina. What makes this song choice interesting for the movie is that it's a song written in Manolete's memory after his death, and it's literally describing his goring in 1947, in Linares. The fact that Adrian Brody's character is actually hearing the song of his coming death is both a fascinating and unsettling directorial/editing decision.
Also known as the title "the passion within" in some countries