"Where are we going to go on Wednesday?"
Translation:Onde nós vamos na quarta-feira?
It was marked correct as "vamos ir," even though "vamos" alone is also accepted. As an English teacher, I can tell you that "where are we going Wednesday" and "where are we going to go Wednesday" mean exactly the same thing (simple future). One may sound better in Portuguese, but it looks like both are still correct.