Yeah, actually several character do make returns and cameos. Lucca play a prominent role in the plot despite the time wraith being the only time you speak to her. Crono and Marle make similar appearances. Balthazar, Schala, and to some extent Robo and the Mother Brain computer are featured in the plot as well. Ozzie, Flea, and Slash all make cameos. Ayla, Magus, and Frog are both mentioned and the Masamune does play a role in the plot, with even dialogue from Masa, Mune, and Doreen. There are tons of refernces to CT for fans and several storylines from CT are intrical to the plot of CC such as the new future Crono made, the Reptites, and the fate of Zeal. My only complaint is that they chose not to put Magus into the game as originally planned.

The amusing thing I didn't relaize until recently is that the DS version of CT actually hints to an explanation for Porre. Masato Kato (scenario writer for Chrono series) says Porre became a military power through "the influence of something beyond the normal flow of time". (SPOILER)The DS version alludes to this force being Dalton who somehow manages to wind up in 1000 A.D. after his run in with the partyduring one of the new sidequests from CT.