There's Something About Mary - S12-E21
Revealing mistake: At the start of the episode when Dean calls Ketch, Dean's phone is not in Call Mode.
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)
Keep Calm and Carry On - S12-E1
Continuity mistake: Dean says his parents met in March 1972. "In the Beginning" was set in April 1973, which means they would have only known each other for one year in that episode, but John said in that episode that Samuel Campbell had been against their relationship for many years.
First Blood - S12-E9
Character mistake: Sam points out Elk Mountain, but there is no Elk Mountain in Rocky Mountain National Park.
Keep Calm and Carry On - S12-E1
Continuity mistake: Mary does not recognize adult Dean and claimed that her Dean is 4 years old. In Season 1 Episode 9: Home, she recognized adult Dean and Sam.
Suggested correction: Mary was a ghost in "Home" and knew that 22 years had passed and her sons would be older now. When the Darkness resurrected her, it was without the memories of her time as a ghost. Mary said so explicitly.
