The idea of secret mission calls was so serious and detrimental to the churches mission that a press conference was held to admonish us to stop spreading the rumors. In it principles were shared to help us understand why these rumors were false. The most important of these being that when the church sends missionaries, we go through the front door. We do it clearly, and publicly, with express consent of the country we are entering. These principles will not change.

In addition, I don't think you have to work in the mission department to see the absurdity behind the thought that the church (which does't send out paper mission calls anymore) is sending out paper mission calls that say "don't open this until after conference! ;D"