Handgun: A 9mm parabellum (possibly an H&K USP).
Sub-Machine Gun: Unmistakably a Heckler & Koch MP5. While not the primary weapon of the US military (as this role is filled by the M16/M4 line) it is issued in large numbers. It likely indicates that the responding personnel are Navy (possibly Marine). This would make sense as the facility is located on an island in Japan.
Grenade: Likely an M67 Fragmentation Grenade utilized by the US military.
Rocket Launcher: Appears to be a modified SMAW. The back of the weapon has a mounting attachment capable of holding a "box" of four rockets. This modification seems to be fictional, but the base weapon (if it is a SMAW) is extensively used by the US military.
Anti-T'lan Laser: A fictional weapon utilizing a high-powered beam capable of killing T'lan.