Playthings - S2-E11
Continuity mistake: In one scene Sam is hung over the toilet from drinking too much with his cast on his left arm. The rest of the show the cast is on his right arm. (00:20:19)
Bloody Mary - S1-E5
Continuity mistake: When the real Jill is being Killed the blood lines from her eyes go from smeared to "clean" lines instantly. (00:14:20)
Continuity mistake: At The End of this episode Dean suggests they go to the Grand Canyon because they have never been, later in the series they talk about John taking them when they were little.
Other mistake: When Dean is listening to Sam's voice mails that he left while in Gary's body, the voice in the recordings are of Sam. If Sam was in Gary's body, they would have been of Gary's voice.
Hell House - S1-E17
Visible crew/equipment: Right before they light the house on fire, the shot cuts the to the hell hound guys and a cameraman is running up to them on the right. Not just an arm - his whole body, including the camera.
Taxi Driver - S8-E19
Continuity mistake: When Crowley comes to the ship and finds Kevin Tran he blew out the glass on the ship to get rid of the sigils. When Sam and Dean get to the ship to check on Kevin, and they notice he's gone, all the glass isn't broken and the sigils are still there.
Bloody Mary - S1-E5
Continuity mistake: When Sam is looking at the mirrors with night vision, we see him pause and say to Dean "Look at this." The camera then cuts to an extreme closeup of the camcorder screen and the image on the screen is different to what was on there before. (00:18:15)
Continuity mistake: At the start as we see the victim on the plane, we see a blonde woman sat in the middle seat 2 rows in front of his row. When he gets up to stretch his legs, this blonde woman has now changed to a Chinese one. (00:02:45)
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)
Continuity mistake: Dean circles the newspaper article on Sophia Carlton. When he hands it to Sam the circle is different. (00:03:20)
Continuity mistake: When the first victim stands up to stretch his legs, he grabs the seat in front of him and his arm is bent. When the shot changes his arm is now straight and he's holding the middle of the seat not the edge. (00:03:00)
Continuity mistake: Season 1 episode 2, Wendigo conflicts with this episode. Originally the wendigo information is printed on the left-hand side of the journal. On the right side is loads of symbols and text. Here the "same" page featuring the wendigo can be seen when Dean and Sam are searching for the asylum information but it's different.
What's Up, Tiger Mommy? - S8-E2
Visible crew/equipment: You can see the crew member's leg go up in the air, and he catches Sam as he runs down the stairs. (00:36:00)
Visible crew/equipment: While Sam Bobby and Dean are talking you can see in the bottom left-hand side a person sitting looking at a camera. (00:17:28)
Revealing mistake: When Max opens the bedroom door to confront his step-mother and Dean, using his telekinesis powers, you can see the equipment used to open the door, a rope pulling the door on the floor. (00:34:19)
All Hell Breaks Loose: Part 1 - S2-E21
Visible crew/equipment: When dean and Bobby drive to the burnt down road house, you can see the boards holding up the wall in the set at the old front door, the boards are set at a right angle to hold the wall up but definitely wouldn't be there it the place was intact.
Back and to the Future - S15-E1
Other mistake: After the spell is cast, the ghosts are chasing Sam, Cas, the mom and the girl towards the safety line...despite ghosts being able to teleport themselves short distances, as they were doing only minutes earlier. They could easily have jumped ahead of them, instead they gave chase on foot.
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: Angel blades come from angels. It's their angelic magic that makes it special. Therefore, an archangel blade is made magical with the powers of an archangel. They couldn't have just created one or used one, as none of them are archangels.