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.
Playthings - S2-E11
Continuity mistake: In one scene Sam is hung over the toilet from drinking too much with his cast on his left arm. The rest of the show the cast is on his right arm. (00:20:19)
All Hell Breaks Loose: Part 1 - S2-E21
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.
All Hell Breaks Loose: Part 1 - S2-E21
Continuity mistake: In the scene where Dean is with Bobby at the burned down Roadhouse and Dean gets Andy's vision about where Sam is, the first time Dean scrunches his face in pain he puts his left hand to his head. The shot changes to a back view and you can tell his left hand is still at his head. But when the shot switches again Dean is bringing his right hand down from his head.
All Hell Breaks Loose: Part 2 - S2-E22
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.
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.