This news is just breaking (from ten days ago when the article was published).
[T]he movie does deal with the paradoxes of time travel: The characters must be careful not to change the future, though one of them wants to set himself up for life a la Back to the Future Part II.
Rob Corddry plays one of the time travelers and tells us he was involved with the decision to tone down the sci-fi. “It’s definitely not, like, a geekfest,” Corddry said in a group interview last week in Valley Village, Calif., on the set of his Adult Swim series Childrens Hospital. “We got together, and there was this writing meeting, like a roundtable, and we talked about time travel for, like, five hours. And then realized that there’s no way to write a time-travel movie where it totally works out, where all the logic works out. If you could do that, then you’d basically figure out time travel.”
But how can I enjoy a comedy about time travel if I know there are logical fallacies in the plot? I only watch movies for scientific accuracy!
But I will bet you that by the time the movie is released on DVD, there will be at least ONE article in a scientific journal with the headline “Could a Hot Tub Time Machine Really Exist?” Trust me, they’ll do it.