Alien Blood: When Exley is struck in the head by a baseball, a few drops of greenish, highly acidic blood are left on a catcher's mitt that had been used to cushion his head. When he's killed by the Alien Bounty Hunter, after declaring that his human face "is my true face", he bleeds differently...
(Arthur Dales cradles the dying Josh Exley, and moves to check his wound.) Exley: Arthur, don't touch it! Our blood is like acid to you people! Get away, Arthur! Just get away! Arthur: It's just blood, Ex... Look. It's just blood... Exley: (looks at the red human blood on his fingertips in wonder and awe) ...How? (smiles, laughs,and dies)
Baseball Episode: Mulder is fond of baseball. Who knew? He bonds with an older cop who tells him a story about fun-loving alien who chose to be a human and play baseball.
Alien Bounty Hunter: As your executioner, I show you my true face before I kill you. (shapeshifts into his alien form) Show me your true face, or you will die without honor. Exley(remaining human) This is my true face... Alien Bounty Hunter: ...So be it.
Game of Nerds: "Reading the box scores, Scully. You'd like it. It's like the Pythagorean Theorem for jocks. It distills all the chaos and action of any game in the history of all baseball games into one tiny, perfect, rectangular sequence of numbers. I can look at this box and I can recreate exactly what happened on some sunny summer day back in 1947. It's like the numbers talk to me, they comfort me. They tell me that even though lots of things can change some things do remain the same."