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..."
Hibbing 911 - S10-E8
Revealing mistake: Sam types the address Donna gave him into an untitled note, which is supposed to act as a Maps search engine. A second later, a map with the address pulls up. His phone also says it's 9:56/9:58 a.m. (00:31:15)
Continuity mistake: As Sam is looking for the next victim in his visions, she walks by with her baby in a stroller. The baby is a completely different looking doll the first two times shown, but is blue-eyed Rosie when Sam approaches and interacts with her. (00:12:30)
Continuity mistake: After Dean zaps the TV with the remote, he lowers his right arm. The next shot behind Dean's right side shows him lowering his arm again.
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)
Continuity mistake: When Jack tries levitating a pencil, the pencil completely vanishes after he sets it down again.
Other mistake: In the original "Scooby-Doo" episode from which this episode is taken from, the house for the reading of the will was on an island as the Mystery, Inc. gang travelled to the house via motorboat. In this episode of "Supernatural", Sam, Dean, and the Mystery, Inc. Crew merely drive up to the house.
Character mistake: Sam describes the books as being from "pre-Biblical lore" and then says they are written in Aramaic. Aramaic was a language during New Testament Biblical times and didn't exist in pre-Biblical times i.e. prior to 4000 B.C.E.
Suggested correction: I believe he meant the book "contained" pre-biblical lore.
First Blood - S12-E9
Character mistake: Sam points out Elk Mountain, but there is no Elk Mountain in Rocky Mountain National Park.
Bloody Mary - S1-E5
Continuity mistake: When Jill's friend is saying how Jill died and mentions her eyes, she has her hands lowered in one shot but raised in the next. (00:16:11)
