Why don't I have a custom title by now?!
Another thing with the blunderbuss, it seems to be missing a fire sound.
It actually is supposed to sound like the SSG's firing sound, which works ok in vanilla, chocolate and prBoom+. ZDoom and GZDoom however mute this sound, perhaps on the basis that the Ultimate Doom IWAD is used. Just another side-effect of a "doom" mod using doom2 features which, I gotta admit, is very unusual and I don't remember it being done in other mods.
Also, a couple of the weapon slots are messed up. I pressed 4 thinking I would pull out the chaingun replacement, but it was the blunderbuss. So I pressed 3 thinking that the slots were swapped, but slot 3 was also the blunderbuss. I was like "WTF", so I pressed 3 again and then it switched to the chaingun.
That's how it's supposed to work, more or less. Picking the "repeating pistol" is assigned to slot 3 (it's essentially a chaingun, but it's de-hacked to trump the normal shotgun), while the "musket" gets assigned to slot 4, trumping the chaingun.
If you cheat with IDKFA, you actually do get 2 weapons in the same slot (3), because the musket is actually the SSG, and you once again have a conflict between Doom and Doom II features, which is handled very differently accross ports. You can't do that in doom.exe or chocolate or prBoom+.
Another oddity was the way the trees break, the offset for the animation is wrong or something. Shoot a tree with the crossbow/rocket launcher, you'll see what I mean.
*shrug* will have to verify that visually, since I didn't touch anything regarding offsets in the PWADs. Chances are they simply did a poor job aligning them. I was surprised to see that the maps themselves were free of mapping errors, though.