A 72-year-old woman had vitreous surgery for epiretinal membrane using the 25-gauge vitrectomy system. During the removal of the cannula at the end of the surgery, half of its tip was noted to be missing. The following day, a severe choroidal detachment associated with a hypotony was found. A second surgery was performed, including drainage of suprachoroidal hemorrhage and choroidal fluid and the removal of the tip of the 25-gauge cannula stuck inside the sclerotomy. The retained cannula tip might have acted as a channel allowing vitreous fluid into the suprachoroidal space, resulting in choroidal detachment, hemorrhage, and hypotony.