At the beginning of the film, Sasha Petrosevitch (Steven Seagal) is briefly seen wielding a stainless or nickel-plated [1911]]-type pistol of unknown make/model, as per the norm in Seagal's movies. It is never seen clearly enough to properly identify. It looks a little like a Kimber Stainless Target II, but this is probably not the right model.
The Heckler & Koch MP5A3 is one of the most commonly-seen weapons in the movie. It is used by the 49ers terrorist group during their assault on Alcatraz, and by many of the FBI agents. The MP5A3s are a mix of models with SEF and Navy-style lower receivers; most also have laser sights.
The Vektor SP1, a South African service pistol that is little-known in the U.S., is the sidearm of choice for most of the 49er terrorists. Sasha Petrosevitch (Steven Seagal) takes one of these pistols from a 49er and uses it for a good part of the film. He also uses a pair of SP1s akimbo during the final shootout, firing them from the crashed helicopter. Nick Frazier (Ja Rule) also uses a Vektor SP1 in several scenes.
FBI Agent Williams (Claudia Christian) carries a Beretta 92FS Inox as her sidearm. She uses a pair of these pistols akimbo in the opening shootout at the chop shop.
Several of the FBI Agents can be seen using Heckler & Koch G36K carbine assault rifles. When the Alcatraz prisoners break into the armory, they also acquire and use several G36Ks.
The prison guards, some of the mercenaries, and most of the FBI Agents carry the standard blued Beretta 92FS as sidearms. Nick Frazier (Ja Rule) uses a pair of these pistols in the chop shop shootout. Due to a continuity error, 49er Six (Nia Peeples) goes from using a pair of Vektor SP1s to using Beretta 92Fs in the final shootout.
Several Taurus PT92s are also seen in the movie as stand-ins for the Beretta 92F (due to continuity errors, these pistols sometimes replace the Berettas in between cuts, even when being wielded by the same character).
Twitch (Kurupt) grabs a Micro Uzi from the Alcatraz armory and uses it in the final shootout. There is a continuity error regarding this weapon; in some shots, his Micro Uzi is a mil-spec model with the side-folding stock, while in other shots, it is a converted civilian Uzi Pistol with no folding stock. Some of Nick's thugs are also seen using Micro Uzis in the chop shop shootout.
When the convicts grab weapons from the Alcatraz armory to fight the 49ers, Little Joe (Michael Taliferro) grabs an FN MAG general-purpose machine gun with no heat shield (the U.S. military equivalent being designated M240G). Of course, in real life, it would be absurd for a prison to keep GPMGs in its armory.
The 49ers bring several rocket launchers with them, which appear to be M72 LAWs fitted with fake RPG-7-style warheads, but this is not certain. In one scene, Twitch (Kurupt) fires one of these launchers at a door, and the movie grossly exaggerates the recoil of the launcher (and Twitch's small stature) by throwing him back several meters into a glass window.
An MG42 light machine gun is used as a remote-controlled turret gun on the crashed helicopter. Nick Frazier (Ja Rule) uses it to shoot down two RPGs fired from less than 50 feet below (in yet another example of this movie's absurdity).
When the convicts are taking weapons from the armory, several Heckler & Koch MG36 light machine guns (recognizable by the bipods) can be seen sitting atop several of the weapons lockers.
