Continuity mistake: When the girl is taking a bath, the water is so full that its almost overflowing. She gets into the tub and the water doesn't overflow. The faucet is still running and yet the water keeps changing from full to down below her shoulders.
Provenance - S1-E19
Other mistake: In the scene where Sam, Dean and Sarah go to compare the painting to the earlier photo of it, Dean, noticing the changed position of the razor, says, "Jared, check it out." He is speaking to the character Sam. The actor's name is Jared. [Confirmed in cast interviews].
Celebrating the Life of Asa Fox - S12-E6
Factual error: At the beginning of the episode it shows it taking place at Emerson Manitoba in 1980. After Mary saves the boy, Asa Fox, she drives him home. Sitting in the driveway is a Maroon GMC Sonoma circa 1994 - 2004. (00:01:45 - 00:02:30)
Continuity mistake: Dean drives the Impala to the coroner's house at the same time Sam is driving Castiel and Jack back to the bunker, also in the Impala. (00:31:15 - 00:33:45)
Continuity mistake: During the scene when Sam and Dean enter the abandoned shipping warehouse to save Charlie, you can see Charlie's legs crossed while sitting in one shot, but in the next shot they are uncrossed. (00:27:10)
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.]
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.
Revealing mistake: As Dean digs into the dead guy's guts and discovers the claw the pale dead guy blinks.
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.
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.
Audio problem: When Dean and Castiel are speaking to the police officer, Dean and Cas say "nothing" and "demons" at the same time. The second time this happens, Cas' voice says demons but his mouth is not moving. (00:11:55)
Visible crew/equipment: Before The End of the episode, Sam and Dean are thanked by the sheriff's daughter and her son. When Sam and the mother are left alone, his microphone wire is visible when he stretches. (00:41:00)
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.
Revealing mistake: When Sam pulls Angela out of the bathtub and on to the floor, you can see the panty line from the nude colored panties she's wearing to keep the show PG13.
Continuity mistake: In the scene where the passengers board the plane at the beginning, the aircraft is a Boeing 737, noticeable by the crew jumpseats located by the entrance door. But the first scene you see where the aircraft is in flight, the aircraft changes to a Widebody Airbus, possibly an A310, noticeable by the different style of winglets that Airbus uses compared to that of Boeing. (00:02:15)
Continuity mistake: Season 6 Episode 15 'The French Mistake': When Sam and Dean are first talking to Misha, the collar of his shirt is tucked into his jacket, as normal. However it suddenly is sticking out over the top of his coat, then changes to being tucked in again, with no time for him to have changed it himself.
The Benders - S1-E15
Continuity mistake: When the Deputy handcuffs Dean to the car door handle, he uses a small radio/cell antenna from the car to pick his handcuff lock (attached to his wrist), just as the bad guys walk toward the car. When the bad guys get to the car Dean is gone and so are the handcuffs (including the cuff that was attached to the door handle). Dean did not have time to pick both handcuff locks.
Revealing mistake: When Dean cuts leviathan-Dean's head off, if you look closely you can see that a) the decapitated head disappears while it is still in the air, and b) when the body recoils, its hands disappear.
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.