When the Titans are watching Sumo on a TV screen, we see 5 teenagers with their backs towards us and one is wearing a red jacket with a blue and pinkish pill on the back of it. This is Kaneda and his gang from the 1988 hit anime Akira by Katsuhiro Ôtomo.
The DVD release has a bonus episode of the Teen Titans called "The Lost Episode." It's a short episode about 10-15 minutes long, regular episodes are usually 18-20 minutes long, which is probably why the "Lost Episode" never made it to air.
The official, U.S. DVD release of the direct-to-video Teen Titans: Trouble in Tokyo was on February 6, 2007. The animated feature first aired on Cartoon Network (US) on September 15, 2006; it premiered at International Comic-Con: San Diego (a.k.a. the San Diego Comic-Con) on July, 22, 2006 - over six months before the DVD release.