We describe a case of radial extension and its management during femtosecond laser-assisted cataract surgery (FLACS) in a patient with intumescent cataracts. Radial extension was observed after injection of trypan blue into the anterior chamber. Management of the extension was achieved by separation of adhesions between the incomplete capsulotomy, along with manual completion at the areas of extensions. Careful observation during FLACS capsulotomy is advised in cases of intumescent cataracts due to the release of cortex into the anterior chamber which may interfere with the delivery of the laser treatment resulting in incomplete capsulotomy patterns. Furthermore, trypan blue staining is essential to identify possible incomplete capsulotomy patterns and extensions. The Argentinian flag sign may occur after femtosecond laser-assisted capsulotomy in cases of intumescent cataracts. Proper identification of incomplete capsulotomy patterns and radial extensions should be managed with careful manual completion of the capsulotomy.