Freeze (Reginald E. Cathey) is seen armed with a Glock 19 during the failed bank robbery. Several of Niko's (Orestes Matacena) thugs during the shootout in the Coco Bongo club are also seen with G19s, one of which has a chrome slide.
Dorian Tyrell's (Peter Greene) sidearm in the film is a Star Firestar M-43 9mm with a nickel finish, which he uses to shoot at Ipkiss/Mask (Jim Carrey) in the Coco Bongo club.
Niko (Orestes Matacena) draws a chrome Jericho 941 R to defend himself during the shootout in the Coco Bongo club. Since Dorian (Peter Greene) is wearing the Mask, he allows Niko to shoot him several times, which has no effect on him. He then sucks up the bullets and fires them out of his mouth, killing Niko.
M1911A1
Sweet Eddy (Denis Forest) is seen using an M1911A1 while in the Coco Bongo club. some of the Edge City Police SWAT officers are also seen using them.
Custom Colt MK IV Series 70
When Niko (Orestes Matacena) plays golf off of Dorian Tyrell's (Peter Greene) mouth, one of his henchmen forces him to stay still by holding a heavily customized Colt MK IV Series 70 (which can be noted by its stamp on the slide) on him. The gun's features target sights, a commander hammer, ornate grips, a beavertail grip safety spur, and a sight rib. The gun is not a Colt Gold Cup National Match as previously suggested, note how the cocking serrations are completely vertical (instead of slanted like a GCNM).
At the end of the film, one of the thugs in the Coco Bongo thug is seen using an unknown Desert Eagle variant with a nickel finish.
Revolvers
Single Action Army
When Ipkiss/Mask (Jim Carrey) imitates a cowboy while under fire from Dorian (Peter Greene) and Orlando (Nils Allen Stewart) in the Coco Bongo club, he is seen with a pair of nickel Single Action Army revolvers, one of which is shot from his hand.
Colt Trooper
Some of the Edge City Police carry Colt Trooper revolvers.
Colt Official Police
Some of the Edge City Police officers attempting to arrest Mask/Stanley Ipkiss (Jim Carrey) outside the park use Colt Official Police revolvers.
Smith & Wesson Model 10 Heavy Barrel
Some of the Edge City Police officers use Smith & Wesson Model 10 Heavy Barrel revolvers. When Stanley Ipkiss (Jim Carrey) escapes from jail, he steals an officer's Model 10HB and uses it to force Lt. Mitch Kellaway (Peter Riegert) to take him to the Coco Bongo club, where he is later disarmed of it by Orlando (Nils Allen Stewart).
Smith & Wesson Model 15
Some of the Edge City Police officers attempting to arrest Mask/Stanley Ipkiss (Jim Carrey) outside the park use Smith & Wesson Model 15 revolvers.
Smith & Wesson Model 19
Some of the Edge City Police officers attempting to arrest Mask/Stanley Ipkiss (Jim Carrey) outside the park use Smith & Wesson Model 19 revolvers.
When a group of street thugs attempt to rob Stanley Ipkiss (Jim Carrey) while he is wearing the Mask, he makes several balloon animals to humor their stupidity before building his "personal favorite", an M1928 Thompson.
Trivia: This scene is one of the few that came from the original "Mask" comic books. In the comics M1928 Thompson was one of the weapons used frequently by Mask.
Sweet Eddy (Denis Forest) wields a pair of Intratec TEC-9s akimbo during the shootout in the Coco Bongo club.
IMI Micro Uzi
One of Dorian Tyrell's (Peter Greene) thugs uses an IMI Micro Uzi during the shootout in the Coco Bongo club.
Rifles
Colt AR-15 A2
Edge City SWAT officers use Colt AR-15 A2s (also called the Colt Government Model HBAR, the civilian version of the M16A2) when trying to arrest Mask/Stanley Ipkiss (Jim Carrey) outside the park.
Shotguns
Mossberg 500
Mrs. Peenman (Nancy Fish) uses a Mossberg 500 shotgun to shoot at Stanley Ipkiss (Jim Carrey) when he first puts on the Mask and wreaks havoc in her apartment. Lt. Mitch Kellaway (Peter Riegert) tells Ipkiss that she fired a couple of rounds of "20-ought-buck", which makes no sense as there is no such thing.
Some of the Edge City Police officers attempting to arrest Mask (Jim Carrey) outside the park use Remington 870 shotguns.
Other
Über-Guns
How else could you describe these? After being barraged by a hail of gunfire, Mask/Stanley Ipkiss (Jim Carrey) shows the thugs what he's packing (after doing his spot on impersonation of Clint Eastwood), which happens to be guns and more guns combined into one gun. After the thugs flee in terror, he reveals they are all "bang" flag guns.
Dorian's Mouth
Using the power of the Mask, Dorian Tyrell (Peter Greene) allows Niko (Orestes Matacena) to shoot him several times (which he shrugs off) and then sucks up the bullets and fires them from his mouth. Since his mouth isn't actually a firearm, this was added to mainly reveal some goofs present.
After Mask/Stanley Ipkiss (Jim Carrey) causes all of the Edge City PD to sing and dance with him, Lt. Mitch Kellaway (Peter Riegert) grabs an Federal L5 Federal Gas Riot Gun and fires it into the air to get the officers' attentions.