Right after Tom, Sarah, Elliott, and Calvin are going kneeboarding, they drop Tom (Steve Martin) back off at the dock. When Tom is walking on the dock you hear Elliott asking him if he's ok and stuff but his lips aren't moving. Then Calvin talks to him and his lips aren't moving either. In fact his mouth is closed.
You might be right, but if you watched this movie on teleision it could just be something wrong with the satellite or something. I was watching the Adventures of Jimmy Neutron once and that happened, but it was jsut my tv.