Audio problem: During lunch at school, Alvin tells an anecdote about Beyonce and all the girls laugh loudly, yet their mouths aren't moving.
Audio problem: Near the end of the movie, Alvin, Brittany, Jeanette and Ellanore are hanging tight to the helicopter. Jeanette jumps down to catch the remote. When she catches it you can hear "Way to go Jean!" Neither Alvin, Brittany, or Ellanore moves their mouth.
Answer: Alvin could have easily known Toby's number and told it to her. Ian just simply put down his phone not even thinking that the chipettes could get at it from inside of the carrier.