In the episode "Provenance" of the series Supernatural. There is NO slip-up. In contrast to previous arguments, Jensen Ackles character "Dean" DOES NOT call his co-star (Jared Padaleki) by his real name. I have personaly reviewed the episode countless times to catch this mistake and i have found out one thing...there isn't one. In the scene where the boys are investigating the haunted painting and Jensen's character "Dean" notices that the strait razor is closed in one picture but open in the other Jensen's character does, in fact, call his co-star by his characters name, Sam.

Although, the line is a bit muffled, you can clear make out "Sam, check this out" and not "Jared." I don't mean any direspect to the individuals who believe that there was a slip-up to be found, i just thought it was necessary to correct their slip-up and make sure that other fans are not mis-lead.