I love the compositing done in 1:17. The background of the train is composited on top of a 3D rendered train interior, with the avatar placed inside it. It looks like the 2D avatar is rendered alongside the interior, seeing as it shares the grainy pattern as the interior when the train moves inside the tunnel. In both the choruses, 1:27/3:09, the outline of the characters cycle through different styles, making them feel more dynamic. Having the JP wiki page for (foam) bubble at 2:58 was also a nice touch.