I report here on a patient with serious complications (lateral rectus muscle injury, orbital fracture, mouth locking, and facial palsy) that were caused by reduction malarplasty. A 32-year-old woman was referred to our department with complaints of inability to move her right eyeball laterally and inability to open her mouth. She has undergone reduction malarplasty 30 days previously at a local clinic. On examination, her maximal mouth opening was less than 3 mm. Her upper lip deviated to the left side when whistling. The orbit was displaced laterally and inferiorly. The upward and lateral gaze were limited. Computed tomography revealed fracture of the right orbital floor and lateral orbital wall extending to the orbital roof. The right lateral rectus muscle showed disconnection. The osteotomized segments were displaced inferiorly, and they pressed on the masseter muscle and coronoid process on the left side. On the 43rd postoperative day, a revision operation for the zygoma and orbit was carried out. Four days after the revision operation, surgery was performed for the myorrhaphy of the lateral rectus muscle and transposition of the medial rectus muscle. This case suggests the possibility of orbital fracture that can occur as a result of sawing in the wrong direction when using the intraoral approach. Although orbital fracture is extremely rare, it is hoped that this case will heighten the awareness of surgeons for this potential orbital fracture.