When Syaoran and co. arrive at Tokyo, instead of wearing the clothes they wore from the Country of Tao (ep. 48-52), they wore the clothes they got from the Country of Record (ep. 40-43). Kurogane even mentions that the previous world they were in was the Country of Records, and not the Country of Tao. From the beginning lines, it's clear that it starts from the end of ep. 42, and follows the manga storyline, as the first lines spoken in Tokyo are the same as those spoken in ep. 43.
The location of the two bases: The Tower and the Tokyo Government Office is eventually the same bases that was used in another Clamp's anime called "X"
Two of the graphics in the opening credits include the magic seal of the Clow and Syaroan's lasenboard from Cardcaptor Sakura. The third is Yuko's seal from
XXXHOLiC (2006).