Continuity mistake: Season 6 Episode 15 'The French Mistake': When Sam and Dean are first talking to Misha, the collar of his shirt is tucked into his jacket, as normal. However it suddenly is sticking out over the top of his coat, then changes to being tucked in again, with no time for him to have changed it himself.
Mannequin 3: The Reckoning - S6-E14
Continuity mistake: When the guys tip Rose into the grave, her eyes are open, but as she lands and dirt falls over her face, her eyes are closed. A dead person's eyes don't close on their own. (00:25:20)
Continuity mistake: When Sheriff Mills and Bobby are talking about transferring Rufus, her lapel goes from being under her seatbelt to over several times in subsequent shots.
Answer: Angels themselves may not have genitalia, but their vessels do. Nephilim occur when an angel in a vessel reproduces.
Greg Dwyer