It makes sense that "it" is implied here, except in other lessons, we have been forced to use "nó" for "it" even when it seems unnatural, and/or have been forced to answer using incomplete english sentences in situations like this. It's just not consistent which can make it very frustrating when you are trying to learn.
semantically speaking, I think it could mean the same. syntactically speaking, I'm not so sure. strictly speaking, I would translate "it's unintentional" as "là vô tình" instead of "không phải là cố tình". now, it's all up to the contributors to add your answer, or refuse it.