A priest of the Catholic Church would attempt to deliver the Last Rites to a fellow priest as he is dying, particularly if that Priest has made a pact with the Devil to save someone else and is certain to burn in Hell forever. Strengthening a dying person in their relationship with God is a principle priestly function, and allowing his fellow priest to give Penance would have essentially saved him from going to Hell.
The bell heard tolling is the sound of the Great Clock of Westminster (also known as 'Big Ben', which is actually the name of the largest bell in the tower). This is not at all in keeping with the Mexican or Vatican settings.