Time Out says
After an accident, scientifically miniaturised marine Quaid finds himself floating, complete with miniaturised submersible, around the body of neurotic wimp Short. The pair's attempts to return him to normal size are hampered by evil saboteurs keen in killing Short in order to get hold of the magical miniaturising whatsit. Where Dante transcended the formulaic ingredients of Gremlins and Explorers by means of dark, droll wit, here for the most part he indulges in frenetic slapstick, broad parody, and juvenile mugging. And while the anatomical special effects are imaginative enough, the manic rather than magical tone fails to achieve the sense of awe that made Fantastic Voyage - clearly this film's inspiration - so fascinating.