The following firearms were seen in the film Mystery Men:
Taurus PT92 Stainless
A modified Taurus PT92 Stainless pistol was used by Disco Boys leader Tony P (Eddie Izzard). Tony P's Taurus PT92 pistol has a gold plated slide and barrel; and custom handgrips (to give the firearm a "disco" appearance), a muzzle compensator, and a holographic red dot sight on top of the pistol's receiver.
A MAC-10 fitted with a flashlight and barrel shroud is seen in the hands of the Susies during the battle with the Mystery Men at Casanova's Mansion.
One of the Suits is seen armed with a chromed Franchi LF-57 submachine gun before it was taken from his hands by the electomagnet on the Mystery Men's armored vehicle. From closer inspection of the firearm, it appears that the chromed LF-57 in Mystery Men is the same firearm used by Kurt Russell in the 1998 sci-fi/action film Soldier.
A Remington 870 is seen in the hands of one of the gang members (possibly a member of the Not-So-Goodie Mob) at Casanova's Mansion. The Remington 870 seen in the film is fitted with a chromed receiver and barrel; a black synthetic foregrip and a synthetic pistol grip.
Skorpion machine pistol
One of the Furriers is seen unloading a two-tone Skorpion SA Vz 61 machine pistol at the Mystery Men's Herkimer battle jinty at Casanova's Mansion.
Heckler & Koch USP Match Stainless
One of the rappers is armed with a Heckler & Koch USP Match with a stainless slide.
A (possible) CAR-15 can be seen among the various guns captured by the electromagnet on the Mystery Men's Herkimer battle jinty.
Jericho 941 R
Another opens fire with a two tone Jericho 941 R.
Dan Wesson revolver
A modified Dan Wesson revolver was seen in the hands of Disco Boys second-in-command Tony C.
Prop pistols and revolvers
The Disco Boys use a variety of handguns were seen in the hands of various gang members at Casanova Frankenstein's mansion later in the film. When the magnet is used, these weapons are seen stuck and are shown to be foam prop replicas.