You can view the solution to the final puzzle [[ PDF ]].
When teams submit the answer "A NEURAL NET", the time traveller again pays them a visit. The team and the time traveler are harassed by a zombie that refuses to go away. The time traveller asks: "Did you figure it out? How do I stop the zombies?"
When the mentions "A Neural Net", the time traveller says: "Oh, that's what this is!". S/he pulls out the neural net and throws over and subdues the zombie.
During the main run, this concluded the hunt.
During the rerun, the time traveller told teams that finished early: "Thanks for your help. I need to get this back to the future, but my time machine the Amyg-DeLorean is broken. I need your help / would you help me? We need to keep the technology out of the zombie hands, so the information is all encoded. I've converted the information into a format for your primitive computers." Teams were then given access to the mini-hunt.