Other mistake: In the final scene the ECG reads in the bottom right corner of the monitor 09:06:12 19 JUL 06. When the Dr. Calls time of death he states 10:41am.
Other mistake: Dean is tied to a chair when Sam rescues him. His hands are tied to the arms of the chair with rope. Sam comes over and just casually loosens the rope and it comes right off, then Dean just simply flings the rope off the other hand like they weren't even tied up, Yet before Sam got there, Dean was struggling to get loose.
Other mistake: When Dean is having fun with the Magic Fingers and listening to music, the song displayed says Led Zepplin - Kashmir. Further listening proves it to not be Zepplin at all. (00:05:45 - 00:06:30)
Tall Tales - S2-E15
Other mistake: When Dean is telling the Trickster that he likes his style it shows the same shot of Dean twice saying "I do, I mean..."
Answer: Angels themselves may not have genitalia, but their vessels do. Nephilim occur when an angel in a vessel reproduces.
Greg Dwyer