De acordo com a entrevista com Pablo Hidalgo (do grupo de histórias de Star Wars) citada em
"Did Galen Erso engineer the faulty exhaust port?"
"Not specifically or else he would have said so in the message. He built an unstable reactor. And it turns out there is a weakness there, but how do you exploit it?"
....
"He knows there's a way to do it... in the novel we get the notion he signed off on the general design plan for these thermal exhaust ports. But he still doesn't have that specific piece of information to pass on, which is why he says 'go get the plans and you'll find it'."