Two gold plated Desert Eagle Mark XIXs are duel wielded at the beginning by Hollywood (Sung Kang) and like your typical Hollywood gun, it manages to fire off much more than what the magazine can hold.
Glock 26
Ryan Maslow (Ben Miles) gives Mika Coretti (Naomie Harris) a Glock 26 for her protection. He mentions that the gun is clean, and it has no serial numbers. Mika uses the Glock throughout the rest of the film, until the Ozunu shootout, when she wields a Beretta Cougar.
Glock 19
Due to a continuity error, the Glock 26 used by Mika Coretti (Naomie Harris) changes to a Glock 19 when Mika escapes the Europol base.
SIG-Sauer P228
The SIG-Sauer P228 appears as the standard issue sidearm to Europol agents. Most noticeable seen during the arrest of Raizo (Rain).
SIG-Sauer P22X
In the beginning, the second of Hollywood's Yakuzas is briefly seen grabbing a P22X from his waist before getting killed by a ninja. It could be either a P220 or a P226, but it's not seen clearly enough to determine it from the single/double-stack bulges or the barrel size.
A Heckler & Koch USP is used by Ryan Maslow (Ben Miles) as his sidearm throughout the film. One is also seen in the hands of a Europol prison guard guarding Raizo, during the warehouse shootout.
Tokarev TT-33
A Tokarev TT-33 can be seen in the hands of the former KGB agent Aleksei Sabatin (Wladimir Tarasjanz) during the flashback of his wife. The TT-33 is anachronistic as the KGB used Makarov PMs.
Rifles / Carbines
Heckler & Koch G36
The Heckler & Koch G36 with ZF 3x4° dual optical sights are used by several Europol police officers throughout the film. Most noticeably during the warehouse shootout and the Ozunu base shootout. They are usually seen with tactical flashlights attached.
Heckler & Koch G36K
The Heckler & Koch G36K is also one of the most common rifles in the film. They are mostly seen fitted with ZF 3x4° dual optical sights and a flashlights. They are used by several Europol agents throughout the whole film. Some people might get the longer G36 and the G36K mixed up in this movie, but this is understandable, since most are seen very briefly or in poor lighting conditions.
Submachine Guns
Heckler & Koch MP5K
A Europol agent is briefly seen with a Heckler & Koch MP5K with an Aimpoint sight during the arrest of Raizo. Ryan Maslow (Ben Miles) uses a plain MP5K during the Ozunu base raid, most notably to fire at Takeshi (Rick Yune). Maslow's MP5K features the Navy trigger group.
Heckler & Koch SP89 (converted to full-auto)
Some of the Yakuzas in the beginning carry Heckler & Koch SP89 submachine guns converted to full-auto and fitted with 30 round magazines.
Heckler & Koch MP5A3
Heckler & Koch MP5A3s are used by a majority of Europol agents. They are usually seen with Surefire dedicated fore-grips and mid-range sniper scopes attached.
Micro Uzi
A Micro Uzi can be seen in the hands of several of Hollywood's Yakuza thugs in the beginning of the film.
Shotguns
Mossberg 500 Cruiser
A Mossberg 500 Cruiser with extended magazine tube can be seen in the beginning in the hands of a Yakuza, but gets killed by the Ninja's kusarigama before he gets a chance to use it.
Franchi SPAS-12
A Franchi SPAS-12 is briefly seen in the hands of a Europol agent during the warehouse shootout. He briefly gets to fire it before his death. It's appearance is very brief and shaky, so screencaps are hard to get.
Machine Guns
FN MAG
FN MAGs are seen mounted on Europol Humvees and APCs during the raid on the Ozunu base.
Launchers & Explosives
CAW 40mm Grenade Launcher
An Airsoft CAW 40mm Grenade Launcher can be seen in the hands of a Europol agent launching flares during the raid on the Ozunu base.
M72 LAW
M72 LAWs can be seen being used by Europol agents during the final shootout.
M67 Hand Grenade
An M67 Hand Grenade can be briefly seen during the Ozunu base raid by a Europol agent to clear a room. It can be easily identified by it's shape.
Other
Fictional Taser (Umarex Walther Red Hawk)
During the arrest of Raizo (Rain), Europol agents can be seen using a fictional Taser. The weapons is actually based on an Umarex Walther Red Hawk (a CO2 powered air pistol with an integral red dot sight) fitted with a barrel extension resembling a Taser cartridge.