When Bobby is talking to Sheriff Jody Mills her uniform collar alternates between under the seat belt and over the seat belt several times.
After Bobby releases Crowley from the glow-in-the-dark devil's trap, he walks onto it. When he does so, the image of the devil's trap can be seen glowing on his jeans. This is not a projection, as some people have surmised. It is actually the material in the jeans reacting to the UV lighting.
After the beginning scene with Bobby & Crowley, they show a park in Kenosha, WI. Dean has his hands in a corpse and turns to talk to Sam. They pan to Sam and when they pan back to Dean again, the corpse blinks.
After the discussion between Rufus and Bobby about stealing the signet ring, the scene switches to Bobby opening his fridge. Inside are a bunch of products carrying the President's Choice logo, a brand only sold in Canada in Loblaw-owned stores. They would likely not be available in Montana.
Where Bobby and Rufus are burying a body in Bobby's yard, when the camera pulls back at the end of the scene, a crew member is visible, standing under a wrecked car. The crew member notices and backs into the shadows.