I don't remember the judge having a 12" revolver

It was in the scene where Jessica shot the gun after Eddie found his wrecked car.

No, Eddie's car was taken by Roger before that. It was seen just before Maroon was killed and then in an alley in Toon Town.

The alley was what I was referencing. The gun was shown moving into the shot (might've been his shadow) then Jessica shot at him.

It was the gun he used to shoot R.K. Maroon and this poster was unorthodoxly reflecting the image of the gun that Eddie saw just before the trigger was pulled. Jessica rabbit let off a round on the Judge making him drop the gun while falling backwards over trashcans.

Very good. You certainly know your stuff.

Memory has always been my most critical gift, especially since I pay close attention to details that may be a benefit in future conversations...and I can admit I like proving people wrong with that logic on my side. *Grins*

It's very possible that he was JD, when you consider the gun and the color of his eyes. Nothing was really known about Pistol Packin' Possum, so it really does seem more factual than anyone ever believed. I never really thought much about it other than the gun similarity, but that was because I never had the chance to get a better look at the poster. You can tell your friend that he's definitely on to something. The only problem I find though is that Eddie never did say what the toon looked like outside of Red, Burning Eyes and a high, squeaky voice

Consider this. It is very likely that Eddie didn't get a clear view of Judge Doom.
What we do know is that he dropped safe on his brothers head. With this in mind Eddie would have had to look up to look up to catch a glimpse of JD, if it was a sunny day or the dead of night, all he would see is a shadow with the red, burning eyes.

I thought his true identity was Christopher Lloyd. :P

Indeed and Roger Rabbit is really a strapping lad called Charles Fleischer.

Huh, interesting theory...