Thought I'd copy my post from the merged Joker props thread. I realize the "doohickey" full auto converter and/or selector has been spotted, but no one else has mentioned that it appears there were two separate prop guns.
Hey guys, just thought I'd post some more info on the gun.
I was watching the Hi-Def opening, and paused in certain areas to get a better look at the Glock.
It's definitely a 17, and it's possible there were multiple filming models. In some shots I see rails on the frame, and in some I don't.
I also think I see a small apparatus at the back of the slide that likely converted the gun to full auto.
Looks to me like there was a different gun in the car scene, with no accessory rails. Then in the bank, the firing model has the rails. Also note the little doo hickey at the back of the slide in the last pic. Possibly a custom job done by the prop gun wrangler?
So it really looks like an older model Glock lower frame in the car scene, and a newer model w/the contoured grips and rails in the bank scenes.