At the dinner table we see everybody having steak with mashed potatoes. But when Chris starts talking, he and Stewie are having roast chicken. On the next cut there is a steak on Brian's plate. When it is back to Stewie, he is having a steak as well, instead of the roast chicken from the previous shot.
When Helen Keller and her teacher Annie Sullivan are speaking in binary, Sullivan is talking to Helen, who attempts to repeat what is said. Helen Keller was deaf and blind, so she couldn't have either seen nor heard Sullivan's words.