Continuity mistake: When Bella first counts her cash, the bills are all in hundreds. The camera changes angles and the bottom bill becomes a fifty.
Fresh Blood - S3-E7
Revealing mistake: Dean cuts himself near the beginning of the episode, however the blood begins to drip (spurt really) before the blade cuts into his arm.
Fresh Blood - S3-E7
Revealing mistake: Sam takes the SIM card out of his phone so it can't be tracked, but when he takes the back off his phone, there's no battery, and the SIM card is just lying in the back not attached to anything! Same for Dean's - he takes the back off and the card just falls right out, not secured in any way as it would be in a real phone.
A Very Supernatural Christmas - S3-E8
Revealing mistake: When the boys are tied up and the pagan gods are preparing for the ritual, the second time they cut into Dean's arm the knife is pressed along his arm and the blood is removed showing no cut at all.
A Very Supernatural Christmas - S3-E8
Continuity mistake: In 'A Very Supernatural Christmas' (S3E08), when the Gods are beginning to sacrifice Sam and Dean, they slice Sam's right forearm. However, at The End of the episode, Sam has his left forearm bandaged, not his right.
Factual error: When Bela shoots at who she thinks is Dean and Sam in bed, it's really blow up dolls. But they don't start deflating until she pulls the covers off them.
Answer: Angels themselves may not have genitalia, but their vessels do. Nephilim occur when an angel in a vessel reproduces.
Greg Dwyer