Recap
In Cape Girardeau, Missouri, Martin Robinson is driving through the night when a truck pulls up behind him at high speed. It slams into the rear of Martin's car and slams into it repeatedly, and then disappears... only to appear ahead of Martin. He brakes to a stop and turns, and the truck chases after him. It finally sends his car off the road, backs away... and disappears...
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Episode Quotes
Sam: By old friend you mean…
Dean: Friend that’s not new.
Sam: Yeah, thanks.
Sam: By old friend you mean…
Dean: Friend that’s not new.
Sam: Yeah, thanks.
Sam: You mean you dated someone? For more than one night?
Dean: Am I speaking in a language you're not getting here?
Sam: You told her. You told her? The secret? Our big family rule number one, we do what we do, and we shut up about it. For a year and a half I do nothing but lie to Jessica, and you go out with this chick in Ohio a couple of times and you tell her everything? Dean!
Dean: Yeah, looks like it
Sam: (talking about Dean and Cassie) What's interesting is that you guys never really look at each other at the same time. You look at her when she's not looking. She checks you out when you look away. It’s just an--an interesting observation, in a, you know, observationally interesting way.
Cassie Robinson: Whenever we get, what's the word, "close," anywhere in the neighborhood of emotional vulnerability, you back off or make some joke or find any way to shut the door.
Dean: Well, that's hilarious. See, I'm not the one who took that big final door and slammed it behind me.
Cassie Robinson: Wait a minute...
Dean: I'm not the one who took the key and buried it.
Cassie Robinson: Are we done with this metaphor?
Sam: I’m guessing you guys worked working things out.
Dean: We’ll be working things out when we’re 90.
Sam: Occasionally I miss boring.
Dean: So this killer truck --
Sam: I miss conversations that didn't start with "this killer truck".
Cassie Robinson: Don't go getting all authoritative on me, I hate it.
Dean: Don't leave the house, please?
Sam: So burning the body had no effect on that thing?
Dean: Sure it did. Now it’s really pissed.
Sam: Where are you?
Dean: I'm in the middle of nowhere with a killer truck on my ass!
Sam: I figured maybe that would get rid of it.
Dean: Maybe?! Maybe?!? What if you were wrong?
Sam: Huh. Honestly, that thought hadn't occurred to me.
Dean: "Well that honestly didn't occur to me." I'm gonna kill him.
Episode Goofs
When Cassie is drinking her tea, in one shot you can see that the cup is completely empty.
When Sam tells Dean to drive the truck to an exact spot, he tells him to drive exactly .7 miles. The first time Dean looks at his odometer it reads 70098.2. The next time he looks at it, it says 70098.4.
However, the third time he looks at it, it reads 70100.3, which is 1.3 miles over the .7 miles he was supposed to drive.

Cultural References
Episode Title: Route 666
The episode title is a reference to Route 66, a transcontinental highway, and the number 666, which in The Bible is a sign of the devil.
U.S. Route 491 was previously named Route 666, but was changed after earning several nicknames, including "The Devil's Highway" and having most of the road signs with the number 666 on them stolen.
Sam: Yeah, kinda like that theatre in Illinois.
This is a reference to The Lincoln Square Theatre in Decatur, Illinois. The theatre is home to the ghost One-armed Red, who was a stagehand that was killed tragically during a performance.