Guarana is a plant native to the Amazon basin (in Brazil). Guarana seed contains twice the caffeine of coffee beans, and is often found in energy drinks.
Traditionally in western movies, cowboys never lose their hats when they fight. This is because there are so many takes of the fight that the director, editor, and actors do not need to worry about continuity; that is, why did the hat come off at one point, but it is back on the head later. In the two fights in this episode, none of the four men loose their hats at any time, even though the fights are quite violent.
Ashmi is a Hindi name meaning "glittering diamond", or possibly translated as '"Rock born, hard and strong, I am."
The episode title is a reference to the 1978 song by Warren Zevon, "Excitable Boy." Its dark lyrics reflect the tone of the episode.