I'm saving the 10's for the game.
The mix of animation styles was a nice touch. The humor was good.
Of course, if they were from the future, they should be able to come back later, I think. The only thing I really know about temporal mechanics is that you shouldn't pay them by the hour.
Check out the Discworld novels, "Pyramids" and "Thief of Time" if you get stuck for ideas.