Before Sam paints the purple man, he takes the brush with his right hand, then he paints with the right hand. After the camera switches he is painting with his left hand and then it goes back to his right hand.
When the Hook Man attacks Sam and Lori in the church... he attacks Sam and Lori in a church. The fact that spirits/demons cannot enter a church (or even pass by one that is burned down) was demonstrated in "Route 666".
When Lori goes to bed there is no lamp connected to the headboard of the bed. But when she wakes and discovers her roommate dead, there is now a gray lamp clamped to the headboard, next to the outside door.
When Sam and Dean go to nine-mile road to hunt the Hook Man, as the cop is coming out of the woods, he yells for Sam to drop the gun. In the background Sam lowers the gun and puts up his hands. But when the shot is on just the brothers, he has the gun pointed at the cop and drops it again.
There is no Eastern Iowa University. There is, however, an Eastern Iowa Community College.
Ankeny is not a "college town." Ankeny only has one community college (DMACC).
"Hook Man" is set in Iowa. Yet in an overhead view as they pull into town, you see palm trees.
Ankeny is in Polk County, Iowa. There is no Calumet County in Iowa; there is a small town in the NW part of the state with the name Calumet, however.
The hook was way too big to have been reforged into a necklace as small as Lori's.
In the last scene, the closed captions showed that Hammerfall's Man on a Silver Mountain was supposed to play but instead played Boston's Peace of Mind. It was probably what the show's producers originally wanted to play but for some reason, changed it.
There is no way that Dean could have dug up the grave alone in that amount of time.
Sam: If it is a spirit, buckshot won't do much good.
Dean: Yeah. Rock salt.
Sam: Huh. Salt being a spirit deterrent.
Dean: Yeah. It won't kill him, but it'll slow him down.
Sam: That's pretty good. You and Dad think of this?
Dean: I told you. You don't have to be a college graduate to be a genius.
(preparing to search)
Dean: All right, take your pick.
Sam: I'll take the house.
Dean: Okay. Hey, stay out of her underwear drawer.
(at a frat party)
Dean: Man, you've been holding out on me. This college thing is awesome!
Sam: This wasn't really my experience.
Dean: Let me guess--libraries, studying, straight As. (Sam nods) What a geek.
Dean: I told him you were a dumbass pledge and that we were hazing you.
Sam: What about the shotgun?
Dean: I said that you were hunting ghosts, and spirits were repelled by rock salt. You know, typical Hell Week prank.
Sam: And he believed you?
Dean: Well, you look like a dumbass pledge.
Dean: So you believe her?
Sam: I do.
Dean: Yeah, I think she's hot, too.
Dean: (digging up an unmarked grave) That's it. Next time, I get to watch the cute girl's house.
Dean: Your, uh, half-caff double vanilla latte's getting cold over here, Francis.
Sam: Bite me.
Dean: So this is how you spent four good years of your life, huh?
Sam: Welcome to higher education.
Lori: So your brother seems very... spiritual.
Sam: He's full of surprises.
"Hook Man" was originally supposed to air right after "Wendigo," the second episode of the season. However, there were issues with the director, David Jackson, who had trouble directing to scare. To resolve the problems, they brought Kim Manners back to re-shoot some scenes and the episode was re-scheduled to air after "Skin."
Denmark: February 19, 2006 on TV3
Portugal: November 20, 2007 on AXN
France: January 8, 2007 on TF6
Italy: March 25, 2007 on RaiDue
Germany: December 3, 2007 on ProSieben
The Netherlands: August 17, 2008 on NET5
Series creator Eric Kripke admitted this was one of his least favorite episodes calling it "Fairly lame and anemic."
Music: Higher Mathematics (Split Habit), Bang Your Head (Metal Health) (Quiet Riot), Noise (Low Five), At Rest (APM), U Do 2 Me (Paul Richards), and Peace Of Mind (Boston)
Dean: Talked the sheriff down to a fine, dude, I am Matlock!
Referring to the TV show that ran from 1986-1995, Matlock (played by Andy Griffith) was a courtroom lawyer who always won his cases.
Dean: Think we'll see a naked pillow fight?
This is a reference to the movie Animal House, where John Belushi's character looks in the window of a sorority house and sees topless girls pillow fighting.
Dean: Nice job, Dr. Venkman
Dean is referring to the Bill Murray character from 1984's Ghostbusters