When Castiel is in the passenger seat, putting his seat belt on before grabbing the wheel from Hael, there is blood splatter seen on the headrests and side walls inside the car, BEFORE they crash into the tree and get bloody.
In "Frontierland" Castiel Misha Collins heals himself from a seemingly mortal wound by touching Bobby's Jim Beaver soul. It seems like Ezekiel/Gadriel Tahmoh Penikett should have been able to do the same thing to heal himself.
The biker Castiel confronts at the payphone is wearing a patch that says "Hardcore biker babe."
When Castiel, Misha Collins, is walking down a forested road the caption reads "Longmont, Colorado." Longmont, Colorado is at the foot of the foothills of the Rocky Mountains IE: the plains.
Nowhere in Longmont is forested. It is all developed.