Supernatural

It looks that the time gap that separates this episode and the previous one is very short. At the end of the previous episode, Dean was heavily battered and bruised by Sam. However, at the beginning of this episode there's no sign of any bruises.

At the very beginning of the episode we see Sam brushing his teeth. However, when he talks to Dean there is no sign of toothpaste in or around his mouth at all.

It's never made clear why the ghouls take so long to kill Sam. They have several opportunities throughout the episode when he's essentially alone and they can dispose of him when Dean is nowhere nearby, but instead they leave him alone.

When the female bartender pours Dean the beer and sits the glass in front of him, the amount of head and the level of beer in the glass changes dramatically from one shot to the next before he even takes his first sip.

Despite his intimate knowledge of the Winchesters, and the fact that in several of his visions their faces are shown, Chuck doesn't recognize Sam and Dean on sight when they arrive at his doorstep.

Chuck asks if they had to live through the ghost ship. However, "Red Sky at Morning" wasn't one of the 24 published books. No explanation is given for why Chuck didn't publish that book (or any of the other 35 missing titles from the list of books seen), even though Dean says they cover "everything."

Trivia: When Sam and Dean force their way into the Chuck's house, you can see a couple of action figures that closely resemble Green Lantern, a DC Comics superhero, near the ceiling.

When Paul was working in the middle of the night trying to retrieve his files, the screen was white with black text. Typically computer "command run" programming section is black screen with white text.

Dean says that his mother's name is Ellen, his father's name is Bob, and his sister's name is Jo. These are characters from the 2nd season. Bob is most likely Bobby Singer. Ellen owned the roadhouse and her daughter Jo worked there until she went off hunting by herself. Sam says that he just broke up with his fiance Madison. Madison was the werewolf that Sam fell in love with in the episode "Heart."

When Pamela starts bleeding, we see blood covering her hand. However, in all the shots following, she is covering her wound with her hand but there's no blood on it.

Even though they're in spirit form, Sam and Dean's condensed breath can be seen when they're speaking in the cold outdoor scenes.

In the opening scene, the clock on the wall has a second hand but it never moves.

While there is a Bedford, Iowa, it doesn't have a major riverfront facility like the one seen at the end, or the huge bridge, or the multi-story buildings. (The bridge is the Skybridge, in Vancouver.)

Cara doesn't notice that she suddenly has a vase of Mediterranean hyacinths in her office. Which means they were already there. However, that means the siren's whole plan to trick Dean rests on the doctor having the one thing in her office that would be a very specific clue to its identity.

In the episode we see the boys interview the husband and he states that if the judge doesn't give him the death penalty, he'll "do it" himself. Yet as a resident of Iowa he would have known that there was no way that would happen since Iowa doesn't have the death penalty. The worst penalty he would have gotten would have been life without parole.

On-screen dialogue establishes that Young Dean and Sam arrive at Truman in November of 1997. However, in the flashback right after Sam says, "Barry had a hard time," a banner can be seen congratulating the seniors of 1997. Either the poster is seven months out of date, or it should refer to the current Class of 1998.

It's unlikely that Sam and Dean would be able to walk free from custody simply by way of Jay dropping the charges against them, particularly given that they would have been carrying firearms at the time of their arrest. Not only that, but presumably they would have been fingerprinted upon arrival at the station; surely that would have raised a few red flags, given that they were pronounced dead by the FBI after the explosion.

While Dean and Sam were at the Milton house they have left evidence of them being there like fingerprints on several objects. They both have their fingerprints in the police database, sooner or later the bodies will be found and evidence will point again to Winchester brothers.

When Sam starts to tell Dean the story about how Ruby saved his life, he is holding a towel to the cut he just stitched up, and his shirt sleeve is bloody from the wound. When the flashback takes a break, Sam hasn't moved from where he was sitting, but his shirt is spotless and there is no blood on his arm or towel stopping the flow.

When Dean and Sam leap out the window, the shot from inside shows the two brothers hitting the window simultaneously. However, when the camera cuts to the outside, Sam emerges first and Dean is considerably behind him.