Other mistake: In the scene where Sam, Dean and Sarah go to compare the painting to the earlier photo of it, Dean, noticing the changed position of the razor, says, "Jared, check it out." He is speaking to the character Sam. The actor's name is Jared. [Confirmed in cast interviews].
Continuity mistake: Before the Roadhouse fire, Ash and Dean are talking on the phone. Ash looks at his watch, on his left hand, it says 8:10, and has a black dial/face. As Dean and Bobby go through the rubble, Dean identifies Ash by his watch. Still on his left hand, it is now upside down, evident by the crown of the watch (used to move the hands of the watch) which previously facing his hand, is now facing his elbow. Also, the dial/face of the watch is now silver instead of black. This is a different watch, and was inadvertently put on the burnt arm upside down.
Question: Not long after first meeting angels, it is established that they do not have genitals, or "junk" as Dean puts it. But in S06E10 Castiel gets an erection while watching porn and in S08E22, Castiel is required to kill a nephilim, the offspring of an angel and a human. If angels do not have genitals how are these two things possible?