Visible crew/equipment: At the start of the episode, the couple comes out of the car and when it pans to show the orchard, a shadow can be seen walking in the lights.
Visible crew/equipment: When Dean thanks the professor before leaving the room, you can see the second camera pan down on the left side of the screen before it cuts to that camera's view. (00:28:40)
Factual error: At the beginning of the episode it is stated that we are in the month of April - yet in the orchard there are ladders, fallen apples and baskets filled with fresh fruit everywhere, as if it were harvest time. The god is declared to grant fertility and not climate change, so the harvest decoration seems definitely out of season.
Answer: Angels themselves may not have genitalia, but their vessels do. Nephilim occur when an angel in a vessel reproduces.
Greg Dwyer