I don't know if I'm missing something but the quiz said that you could acceptably translate "I need to go to the toilet" as "J'ai envie d'aller etc..."
Surely that's wrong - wouldn't you only use that form of words if you were expressing a desire to go to the toilet, but not a need? (Admittedly, I can't think of a circumstance where you'd say 'I really feel like a visit to the toilet right now ..!')