Audio problem: When Dean puts the cassette in the car stereo he reads 'Metallica' off it, yet AC/DC plays. [In the original version Metallica was played, but AC/DC was used in newer versions due to copyright issues.]
Audio problem: The pilot asks Amanda how she is at the start. When Amanda replies the audio doesn't match her mouth. (00:02:10)
Provenance - S1-E19
Audio problem: When Sarah goes to touch Evelyn's shoulder, you hear Sam's voice telling her to stop, except his mouth isn't moving at the time the phrase is being uttered. (00:23:50)
Answer: Angels themselves may not have genitalia, but their vessels do. Nephilim occur when an angel in a vessel reproduces.
Greg Dwyer