There was another Zonk in last week's episode of 'Supernatural', and luckily for me, the writers chose just to make the reference and move on. I think it may have been a matter of pride - if there were people out there in the audience who didn't know what 'The Rockford Files' was, then the writers didn't want to think of them as part of their demographic.....
Trusting in Diane Ballard, Dean told the Baltimore detective where she could find his brother Sam: that he was staying in a local motel under the alias of "Jim Rockford". Dean splained that it's the name they always use on the road.
In their line of work, Sam and Dean Winchester would need the help of various people all across the country. Their father used to have such a network of allies - other paranormal investigators, cops, doctors, bounty hunters, and private eyes.
Again, we're dealing with untold stories in the saga of the Winchester boys, but it's possible that while investigating a case out in Los Angeles, they called upon the services of a retired private investigator named Jim Rockford.
I would imagine that the three of them would have meshed; that their personalities, sensibilities, and list of likes and dislikes would have made the working relationship click. Even if the Rockfish found their line of work to be totally bonkers.
I would think the Winchester brothers would have come away from the encounter with a deep appreciation for the private eye and a desire to emulate him in some small way. So as a tip of the hat, as they crossed the country they invoked his name when staying in motels while separated from each other.
It could even be a trick Rockford taught them, and so they invoke his name in honor.
It's not like they were ever going to run across a desk clerk who knew the original. After all, Sam and Dean would have realized that Jimbo rarely travelled too far from his trailer on the beach......
It's the sort of situation that has come up before on other shows; just this season in fact. Private investigator Keith Mars of Neptune, California, and the father of 'Veronica Mars', used the name Adrian Monk as his cover while investigating a case.
Despite the fact that they live at either end of the state of California ('Monk' is a resident of San Francisco.), it's not unlikely that Keith met Adrian in the course of them both performing their duties, either as private investigators or as police officers in their earlier lives.
As a matter of fact, by the end of last season, Keith had gone north to bring Woody back to Neptune. Who's to say on his road trip back (having eschewed a seat on that doomed flight) that he didn't go to the City by the Bay for a quick chance to touch base with the obsessive compulsive detective in regards to another case?
I'm sure there's a fanficcer out there somewhere who's already come up with a way to bring the two shows together.
And this time, Adrian Monk will be invoking Keith Mars' name in order to make everything even.
They'll thank me later......
'The Rockford Files'