In the Blue Skiddoo segment, Jane introduces her friend Carly as being deaf. Carly, however, can hear just fine, she just can't speak, meaning that she is mute and not deaf.
Mailtime Segment: Mailbox shows off that he has a sign: his flag. In the letter, a group of kids uses signs to say good morning to various people. But the boy says "Good morning, friends" without using sign language.