Note that all the screencaps are fairly low-grade. If someone can obtain higher-quality images to replace them with, that would be just peachy - Plus it could help to identify or confirm some of the weapons.
The following weapons are seen/used in the film Nothing But Trouble:
The most prominent weapon in the film, the Spectre M4 SMG is carried by Valkenvania Police Chief Constable Dennis Valkenheiser (John Candy), and used by Constable 'Miss Purdah' (Valri Bromfield). The Spectres in this film have the foregrips and folding-stocks removed.
CAR-15
The main weapon carried (but never fired) by Miss Purdah is a CAR-15 rifle.
XM177E2
Interestingly enough, in one part of a scene, Miss Purdah has what appears to be an XM177E2 rifle slug on her back. Perhaps possibly standing in for the CAR-15.
Colt Detective Special
The drunk crook Arthur (Daniel Baldwin) pulls a later-made nickel-plated Colt Detective Special (unknown caliber) on Dennis, though it gets quickly knocked out of his hand. It is seen again a bit later in the courtroom on the desk of Judge Alvin Valkenheiser (Dan Aykroyd).
Beretta 92F
As Judge Alvin Valkenheiser examines the confiscated items, including the Colt shown above, a Beretta 92F semi-auto pistol can be seen on the desk.
-- I don't know about you but if I'm still seeing straight, I'd say that ain't no rounded trigger-guard. So it's more likely a 92F. --Warejaws 13:52, 8 March 2010 (UTC)
Bah, you're right - I can't believe I thought that was a rounded-guard.. so silly. I'll fix it up.
Walther PPK
Alvin's personal weapon appears to be a stainless Walther PPK pistol. The pistol in this film appears to have some kind of engraving on the slide.
Ruger Mini-14
Miss Purdah carries and fires a Ruger Mini-14 rifle with scope and stainless barrel/receiver at Chris and Diane as they escape the Valkenhesier Salvage towards a train.
Mossberg 500AT
When Chris and Diane have the State Police raid the Valkenheiser Salvage near the end of the film, some of the troopers carry what appear best to be standard Mossberg 500AT shotguns (wooden furniture), which I figure mainly because of the dual-action bars.
M16A1
Guardsmen accompany the State Troopers on the raid, and they are armed with M16A1 rifles with 20-round magazines.
Unknown Revolver
An unknown full-sized revolver (My guess would be a Colt) is wielded by a State Trooper on the raid.
Unknown Bolt-Action Rifle
Another State Trooper takes position with a scoped bolt-action rifle of unknown Make/Model.
Unknown Pistols
Dual pistols carried by Miss Purdah in reverse-draw holsters. The distance plus low quality of the image makes them very difficult to identify, but I've added them anyway for the sake of completeness.