After Toto escapes from the mean lady's basket, and jumps into Dorthy's window there is a box ( in the far right side of the screen) and it says Tota not Toto.
Um, you are wrong. The box does not say "Tota," it says "Toto." The word is written in cursive. That is why there is a little "tail" on the end of the second "o." It is obviously an "o" because the cursive "o tail" extends from the top of the letter "o," not down to the base of the imaginary line on which the word is written. Did you not learn cursive in grammar school?
There really is a slip-up with the dogs name...but this isn't it. At the end of the movie, the credits say "Toto as TOTO", but Toto's actual real life name was Terry.