This is great I liked the plot I just think the animation could be a little better, for example when you have the grunts move for more natural movement, you can have it so right as they finish moving it slows to a stop, so you move the part less and less each frame.
edit: its used for most movement although usually not for punches cause that would be a sudden stop from the impact
also just a thought: if you wanted the time traveler to not look like he was part of the aahw you could have recolored his glasses or something so there would be a noticeable difference