Continuity mistake: The baby gets into the fridge, which then closes - we see a closeup shot of the babyproofing clip shutting itself. Then when the mother sees the spilled milk and realises what's happened, there are a few shots of the fridge - in shots from the front the clip's open, and in shots from the side it's closed. When she goes to open the fridge it's open again - she even fiddles with it to give the appearance of undoing it before opening the fridge door.
Continuity mistake: During the scene where Sam is tied up and eventually fights the fake-Dean in Becka's house, there is a shot that shows both his feet and hands tied. During the fight, both his hands and feet are shown free, but he only cut free his hands, and began fighting immediately after that.
Continuity mistake: When Dean reads about the Roosevelt Asylum in his dad's journal, there is a picture of a Wendigo on the opposite page of the newspaper clipping but in a different scene, Dean checks the article again for information on the South Wing in the Asylum but this time on the opposite page of the newspaper clipping, there is no picture.
Continuity mistake: In the scene when John is talking to Mr. D in the diner, Mr. D tells John to "say hello to your old man for me." It is later revealed in season 8 that John's father left them when he was young. This is a mistake, unless Mr. D is referring to John's grandfather (unlikely).
Continuity mistake: Before the Roadhouse fire, Ash and Dean are talking on the phone. Ash looks at his watch, on his left hand, it says 8:10, and has a black dial/face. As Dean and Bobby go through the rubble, Dean identifies Ash by his watch. Still on his left hand, it is now upside down, evident by the crown of the watch (used to move the hands of the watch) which previously facing his hand, is now facing his elbow. Also, the dial/face of the watch is now silver instead of black. This is a different watch, and was inadvertently put on the burnt arm upside down.
Continuity mistake: When Dean kisses the Crossroads Demon, his head is tilted left, but when it cuts to the next shot his head is tilted to the right. It switches back and forth in the next two shots too quickly for Dean or the demon to move their heads.
Revealing mistake: Sam takes the SIM card out of his phone so it can't be tracked, but when he takes the back off his phone, there's no battery, and the SIM card is just lying in the back not attached to anything! Same for Dean's - he takes the back off and the card just falls right out, not secured in any way as it would be in a real phone.
Continuity mistake: Near the end of the episode when Dean is being chased by the possessed truck, Sam tells him to take a left. After he's made the left, Sam tells him to go exactly 7/10ths of a mile and stop. Dean looks at his gage and it reads 70098.3. Dean looks up, then back at it: it changes to 70098.5, but the next time he looks down it says 70100.6 and when he stops it says 70101.0, meaning he's gone 2 miles too far. (Probably meaning it took two shots to get the scene right but they messed up on the gage.)