Samhain is not pronounced "Sam hayne" Rather, it is pronounced sow-in as it is a Gaelic word and, thus, a Gaelic pronunciation
The drawings of Sam Hain that Sam shows to Dean are actually Gustave Dore's illustration of Dante's Inferno from The Divine Comedy and have nothing to do with Sam Hain.
When introducing themselves to the pottery teacher, the brothers introduce themselves as Agent Geddy and Agent Lee.
Geddy Lee is a Canadian musician and songwriter, best known as the lead vocalist, bassist, and keyboardist for the Canadian rock group Rush
Uriel's status in Christian and Jewish traditions is circumspect. Up until the Council of Rome in 745 he was accepted by the Catholic Church, however, during the Council of Rome he and other Angels were struck with only three remaining: Michael, Gabriel, and Raphael. The others were struck in an effort to curb Angelic worship. Uriel is not mentioned in any Western accepted Biblical text. Rather, he appears in the apocryphal books not accepted by any western Christian church. Despite this, he was venerated in the Anglican Church as well as in other Eastern Orthodox and Oriental Orthodox communities.