Doom is a 2005 sci-fiction horror film, based on the popular video games developed by id Software. The movie takes place on Mars in the year 2046, and stars Karl Urban and Dwayne "The Rock" Johnson as members of the RRTS (Rapid Response Tactical Squad) tasked to investigate the happening at the Union Aerospace Corporation (UAC) Olduvai Research Facility. Johnson's role, "Sarge" is based on the character Master Sergeant Thomas Kelly from Doom 3, and the overall plot is loosely based on that of the game as well. The movie was directed by Andrzej Bartkowiak (Exit Wounds, Romeo Must Die and Cradle 2 the Grave).
The following weapons were used in the film Doom:
Heckler & Koch USP
Some of the marines including Mac (Yao Chin), Duke (Razaaq Adoti) and Reaper (Karl Urban) use H&K USP handguns with stainless-steel barrels as their sidearms. It is most notably seen when Mac hands one to Pinky (Dexter Fletcher) for protection.
IMI Desert Eagle Mark XIX
Sarge's (Dwayne Johnson) sidearm is an IMI Desert Eagle Mark XIX. He most notably uses it to kill a mutated Dr. Carmack (named after John Carmack, one of the videogame Doom's creators) and to kill an unconcious infected scientist when he and the others return to earth. He most likely discards of the weapon when he runs out of ammunition as he is not seen with it before his showdown with Reaper. His gun is quite clearly the .44 Magnum version, as evidenced by the fluted barrel in the screenshot below.
Heckler & Koch G36 (modified)
The Heckler & Koch G36 visually modified is the futuristic rifle carried by Sarge (Dwayne Johnson), Reaper (Karl Urban), Portman (Richard Brake), and Duke (Razaaq Adoti). Mac (Yao Chin) also carries what appears to be one of these rifles with some sort of grenade launcher attachment. According to the ammo counters, the beefed-up box magazines are supposed to hold 65 rounds.
Heckler & Koch MP5K (modified)
Benelli M3 Super 90 (modified)
Browning M1919A4E1 (mocked up as a Handheld Minigun)
Destroyer (Deobia Oparei) uses a minigun which is actually built over a World War II Browning M1919. More specifically it appears to be the Browning M1919A4E1 judging by the bolt retracting bar visible in the behind the scenes images. The M1919A4E1 was designed for use in armored vehicles, with the bolt retracting bar allowing the machine gun to be operated more easily from inside a turret. It is built to resemble a man-portable version of the General Dynamics GAU-19/A.
Bio Force Gun v3.14
The Bio Force Gun, adapted from the game's BFG 9000, also makes an appearance in the movie: "Bio Force Gun" is a name invented by the film, but Sarge comments with what "BFG" actually stands for when he encounters the weapon. Like the game, it's the most destructive weapon used, though it does not function in the same way, firing something more akin to a large ball of glowing acid. In fact, any BFG variant from any game in the Doom or Quake series would have killed Sarge if he used it the way he does in the film. It is wielded by Sarge (Dwayne Johnson). There were two working (vibrating) props of The Bio Force Gun, built from scratch out of resin and fiberglass.
Several highly modified real-life weapons can be seen in the armory. The majority of these guns were actually airsoft weapons; most of them were eventually sold by PropStore.
Mac carries what appears to be a modified or artificial grenade launcher type weapon attached to his rifle. This however, cannot be confirmed as the weapon is never fired in the film.