This episode features almost every character in the series at some point (even those that are dead) in the episode.
-Gato's thugs, Tazuna, Tsunami, Inari, Team Oboro, Dosu Kinuta, Zaku Abumi, Gaara, Hayate Gekko, Kabuto, the Sound Four, Itachi Uchiha, Kisame Hoshigaki, the ANBU Black Ops, Choza Akimichi, Zabuza Mamochi, and Haku are seen standing in line at the bathroom.
-Naruto passes by Inochi Yamanaka, Shikaku Nara, the Fourth Hokage, Shizune, Kakashi Hatake, Kurenai Yuuhi, and Asuma Sarutobi in the hallway.
-Pakkun and Akamaru are seen near the portable stalls.
-Ton Ton, Gamakichi, and Gamatatsu are seen near the bathroom outside.
This was all done for fun.