User blog comment:Brian Linder/TMNT Video: Tell Us What You Spotted/@comment-6005022-20140811141950/@comment-167456-20140811200409

Michelangelo skateboards in the sewer in the opening of the 2003 series too (behind his brothers, who are on a bike, a scooter and rollerblades). There's even a level in one of the video games that is just Mikey skateboarding in a sewer: https://www.youtube.com/watch?v=Qjtyu3KHUvA

Sewer skating in general goes back to at least the 1990 film (https://www.youtube.com/watch?v=JuRE9X-eU7k).