Professor and Class Laughed When Asking About Overflow In Project. Did I do something wrong?
Assuming that there are no missing information on the situation:



Your question does make perfect sense. Overflows are a serious flaw that can lead to security problems, not a laughing matter. 

However, I can see myself leading the students to an overflow as motivation to explain how to deal with them, that might include answering your question with the same words your professor used (to not disrupt the 'plan' for the topic - Indeed, I did that a couple of times already). 

This would not, however, include me laughing (a smirk maybe), and I would certainly not tolerate that reaction from your colleagues, which would lead me to reveal what I was planning and that your question was not only valid, but the point of the whole thing. 

Ignore the reaction of the class. Herd mentality... As if they knew any better :)

On a side note, who teaches visual basic nowadays? :)