When Tim and Kat touch their glasses together in a toast, the glasses make a distinct ringing sound. However, they both are holding their glasses by the bowl, which would result in a clink rather than a ring.
In the scene where Kat has brought her mom pizza down at the docks Mrs. Araujo asks, "Hey, Sylvio, you got a job for my smart kid?" Sylvio shakes a dead octopus at her and replies something along the lines of, "Yeah, right here" but is smiling broadly the whole time and does not move his lips.
Immediately after the food critic gives his glowing report on TV, the wall phone at Mystic Pizza rings. The shot shows the owner answering the phone, but it also shows the business license on the wall next to the phone. The license clearly reads "Town of Groton" instead of Mystic.