On the official Teenage Mutant Ninja Turtles Twitter and an official press release, Nickelodeon has described this episode as not being canon to the main story-line and taking place in "another dimension."
This episode and the two that follow it are set fifty years in an alternate future.
This series of the Turtles includes many nods and homages to TMNT of other media. This particular story line is inspired by the 1986 Roleplaying game, "Teenage Mutant Ninja Turtles: After the Bomb," originally published by Palladium Books. It features mutant animals, anthropomorphic and otherwise, in a post-apocalyptic setting.
The fuel barrels that Donbot grabs from the back of the Shellraiser are labeled "Tromaville," a reference to the hometown of The Toxic Avenger and the frequent fictional setting of many films made by Troma Entertainment.