The uninvolving plot in this Douglas Adams-wannabe sci-fi tale concerns two vaudeville comics caught in a terrorist scheme while they look for intergalactic gigs. It’s just a setup (and not a very good one at that) that allows Idle to use the pair’s robot companion to ponder the meaning of humor. Shouldn’t an ex-Python know that nothing is less funny than analyzing comedy? Yet he indulges in witheringly banal musings like why the letter k is comical and whether a pie in the face would get a laugh if no one were there to see it. (Nope.) The Road to Mars isn’t funny whether you read it or not.