Kamui's Dimension (Literally meaning: Kamui's time–space dimension) is an alternate space that was created by Obito Uchiha's Mangekyo Sharingan. Kakashi Hatake's and Obito's Kamui share this same dimension when teleporting objects, due to the fact that each has one of Obito's eyes. This is further evidenced by the fact that objects warped by the former ability were still able to interact with Obito, despite his otherwise comprehensive "intangibility". Prior to learning the reason of this connection, Kakashi exploited it to injure Obito, still under the guise of Tobi, during the Fourth Shinobi World War.
Due to the two eyes being the only known pathways into and out of this dimension, there seems to be no other way of escaping it.