Fan Casting All back to normal... right? in The Teenage Mutant Ninja Turtles: Time, Space, & Other Stuff

After saving earth from destruction with thanks to The Fugitoid's time-travelling ship, the Turtles manage to defeat (and supposedly kill) Shredder this time before he can kill Splinter. The family is reunited, but something seems off... which might have something to do with a strange glowing cube left behind in Central Park.