A case of uncommon fluid extravasation during knee arthroscopy leading to a swelling of the groin, scrotum, and penis, with massive intraperitoneal and retroperitoneal fluid accumulation is reported. A defective pump pressure sensor relay was found to be the cause of uncontrolled fluid delivery with excessive intra-articular pressure increase. The literature reports several cases of extravasation of irrigation fluid into the calf without any sequelae. Our patient experienced proximal expansion of the fluid that expanded along the vastus intermedius and shunted into the retroperitoneal and intraperitoneal space. There was no clinical evidence of compartment syndrome despite the excessive amount of extravasation in the thigh. Diuretics were administrated, and the fluid was excreted within 36 hours. The patient suffered of no further sequelae.